memory.c 106.2 KB
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/*
 *  linux/mm/memory.c
 *
 *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 */

/*
 * demand-loading started 01.12.91 - seems it is high on the list of
 * things wanted, and it should be easy to implement. - Linus
 */

/*
 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
 * pages started 02.12.91, seems to work. - Linus.
 *
 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
 * would have taken more than the 6M I have free, but it worked well as
 * far as I could see.
 *
 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
 */

/*
 * Real VM (paging to/from disk) started 18.12.91. Much more work and
 * thought has to go into this. Oh, well..
 * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
 *		Found it. Everything seems to work now.
 * 20.12.91  -  Ok, making the swap-device changeable like the root.
 */

/*
 * 05.04.94  -  Multi-page memory management added for v1.1.
 * 		Idea by Alex Bligh (alex@cconcepts.co.uk)
 *
 * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
 *		(Gerhard.Wichert@pdb.siemens.de)
 *
 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
 */

#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
#include <linux/pagemap.h>
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#include <linux/ksm.h>
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#include <linux/rmap.h>
#include <linux/module.h>
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#include <linux/delayacct.h>
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#include <linux/init.h>
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#include <linux/writeback.h>
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#include <linux/memcontrol.h>
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#include <linux/mmu_notifier.h>
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#include <linux/kallsyms.h>
#include <linux/swapops.h>
#include <linux/elf.h>
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#include <linux/gfp.h>
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#include <asm/io.h>
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#include <asm/pgalloc.h>
#include <asm/uaccess.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/pgtable.h>

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#include "internal.h"

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#ifndef CONFIG_NEED_MULTIPLE_NODES
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/* use the per-pgdat data instead for discontigmem - mbligh */
unsigned long max_mapnr;
struct page *mem_map;

EXPORT_SYMBOL(max_mapnr);
EXPORT_SYMBOL(mem_map);
#endif

unsigned long num_physpages;
/*
 * A number of key systems in x86 including ioremap() rely on the assumption
 * that high_memory defines the upper bound on direct map memory, then end
 * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
 * and ZONE_HIGHMEM.
 */
void * high_memory;

EXPORT_SYMBOL(num_physpages);
EXPORT_SYMBOL(high_memory);

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/*
 * Randomize the address space (stacks, mmaps, brk, etc.).
 *
 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
 *   as ancient (libc5 based) binaries can segfault. )
 */
int randomize_va_space __read_mostly =
#ifdef CONFIG_COMPAT_BRK
					1;
#else
					2;
#endif
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static int __init disable_randmaps(char *s)
{
	randomize_va_space = 0;
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	return 1;
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}
__setup("norandmaps", disable_randmaps);

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unsigned long zero_pfn __read_mostly;
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unsigned long highest_memmap_pfn __read_mostly;
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/*
 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
 */
static int __init init_zero_pfn(void)
{
	zero_pfn = page_to_pfn(ZERO_PAGE(0));
	return 0;
}
core_initcall(init_zero_pfn);
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#if defined(SPLIT_RSS_COUNTING)

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static void __sync_task_rss_stat(struct task_struct *task, struct mm_struct *mm)
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{
	int i;

	for (i = 0; i < NR_MM_COUNTERS; i++) {
		if (task->rss_stat.count[i]) {
			add_mm_counter(mm, i, task->rss_stat.count[i]);
			task->rss_stat.count[i] = 0;
		}
	}
	task->rss_stat.events = 0;
}

static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
{
	struct task_struct *task = current;

	if (likely(task->mm == mm))
		task->rss_stat.count[member] += val;
	else
		add_mm_counter(mm, member, val);
}
#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)

/* sync counter once per 64 page faults */
#define TASK_RSS_EVENTS_THRESH	(64)
static void check_sync_rss_stat(struct task_struct *task)
{
	if (unlikely(task != current))
		return;
	if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
		__sync_task_rss_stat(task, task->mm);
}

unsigned long get_mm_counter(struct mm_struct *mm, int member)
{
	long val = 0;

	/*
	 * Don't use task->mm here...for avoiding to use task_get_mm()..
	 * The caller must guarantee task->mm is not invalid.
	 */
	val = atomic_long_read(&mm->rss_stat.count[member]);
	/*
	 * counter is updated in asynchronous manner and may go to minus.
	 * But it's never be expected number for users.
	 */
	if (val < 0)
		return 0;
	return (unsigned long)val;
}

void sync_mm_rss(struct task_struct *task, struct mm_struct *mm)
{
	__sync_task_rss_stat(task, mm);
}
#else

#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)

static void check_sync_rss_stat(struct task_struct *task)
{
}

#endif

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/*
 * If a p?d_bad entry is found while walking page tables, report
 * the error, before resetting entry to p?d_none.  Usually (but
 * very seldom) called out from the p?d_none_or_clear_bad macros.
 */

void pgd_clear_bad(pgd_t *pgd)
{
	pgd_ERROR(*pgd);
	pgd_clear(pgd);
}

void pud_clear_bad(pud_t *pud)
{
	pud_ERROR(*pud);
	pud_clear(pud);
}

void pmd_clear_bad(pmd_t *pmd)
{
	pmd_ERROR(*pmd);
	pmd_clear(pmd);
}

/*
 * Note: this doesn't free the actual pages themselves. That
 * has been handled earlier when unmapping all the memory regions.
 */
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static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
			   unsigned long addr)
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{
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	pgtable_t token = pmd_pgtable(*pmd);
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	pmd_clear(pmd);
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	pte_free_tlb(tlb, token, addr);
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	tlb->mm->nr_ptes--;
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}

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static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pmd_t *pmd;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
		if (pmd_none_or_clear_bad(pmd))
			continue;
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		free_pte_range(tlb, pmd, addr);
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	} while (pmd++, addr = next, addr != end);

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	start &= PUD_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PUD_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pmd = pmd_offset(pud, start);
	pud_clear(pud);
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	pmd_free_tlb(tlb, pmd, start);
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}

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static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
				unsigned long addr, unsigned long end,
				unsigned long floor, unsigned long ceiling)
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{
	pud_t *pud;
	unsigned long next;
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	unsigned long start;
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	start = addr;
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	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(pud))
			continue;
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		free_pmd_range(tlb, pud, addr, next, floor, ceiling);
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	} while (pud++, addr = next, addr != end);

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	start &= PGDIR_MASK;
	if (start < floor)
		return;
	if (ceiling) {
		ceiling &= PGDIR_MASK;
		if (!ceiling)
			return;
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	}
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	if (end - 1 > ceiling - 1)
		return;

	pud = pud_offset(pgd, start);
	pgd_clear(pgd);
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	pud_free_tlb(tlb, pud, start);
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}

/*
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 * This function frees user-level page tables of a process.
 *
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 * Must be called with pagetable lock held.
 */
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void free_pgd_range(struct mmu_gather *tlb,
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			unsigned long addr, unsigned long end,
			unsigned long floor, unsigned long ceiling)
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{
	pgd_t *pgd;
	unsigned long next;
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	/*
	 * The next few lines have given us lots of grief...
	 *
	 * Why are we testing PMD* at this top level?  Because often
	 * there will be no work to do at all, and we'd prefer not to
	 * go all the way down to the bottom just to discover that.
	 *
	 * Why all these "- 1"s?  Because 0 represents both the bottom
	 * of the address space and the top of it (using -1 for the
	 * top wouldn't help much: the masks would do the wrong thing).
	 * The rule is that addr 0 and floor 0 refer to the bottom of
	 * the address space, but end 0 and ceiling 0 refer to the top
	 * Comparisons need to use "end - 1" and "ceiling - 1" (though
	 * that end 0 case should be mythical).
	 *
	 * Wherever addr is brought up or ceiling brought down, we must
	 * be careful to reject "the opposite 0" before it confuses the
	 * subsequent tests.  But what about where end is brought down
	 * by PMD_SIZE below? no, end can't go down to 0 there.
	 *
	 * Whereas we round start (addr) and ceiling down, by different
	 * masks at different levels, in order to test whether a table
	 * now has no other vmas using it, so can be freed, we don't
	 * bother to round floor or end up - the tests don't need that.
	 */
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	addr &= PMD_MASK;
	if (addr < floor) {
		addr += PMD_SIZE;
		if (!addr)
			return;
	}
	if (ceiling) {
		ceiling &= PMD_MASK;
		if (!ceiling)
			return;
	}
	if (end - 1 > ceiling - 1)
		end -= PMD_SIZE;
	if (addr > end - 1)
		return;

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	pgd = pgd_offset(tlb->mm, addr);
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	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(pgd))
			continue;
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		free_pud_range(tlb, pgd, addr, next, floor, ceiling);
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	} while (pgd++, addr = next, addr != end);
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}

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void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
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		unsigned long floor, unsigned long ceiling)
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{
	while (vma) {
		struct vm_area_struct *next = vma->vm_next;
		unsigned long addr = vma->vm_start;

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		/*
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		 * Hide vma from rmap and truncate_pagecache before freeing
		 * pgtables
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		 */
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		unlink_anon_vmas(vma);
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		unlink_file_vma(vma);

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		if (is_vm_hugetlb_page(vma)) {
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			hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
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				floor, next? next->vm_start: ceiling);
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		} else {
			/*
			 * Optimization: gather nearby vmas into one call down
			 */
			while (next && next->vm_start <= vma->vm_end + PMD_SIZE
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			       && !is_vm_hugetlb_page(next)) {
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				vma = next;
				next = vma->vm_next;
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				unlink_anon_vmas(vma);
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				unlink_file_vma(vma);
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			}
			free_pgd_range(tlb, addr, vma->vm_end,
				floor, next? next->vm_start: ceiling);
		}
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		vma = next;
	}
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}

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int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
		pmd_t *pmd, unsigned long address)
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{
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	pgtable_t new = pte_alloc_one(mm, address);
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	int wait_split_huge_page;
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	if (!new)
		return -ENOMEM;

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	/*
	 * Ensure all pte setup (eg. pte page lock and page clearing) are
	 * visible before the pte is made visible to other CPUs by being
	 * put into page tables.
	 *
	 * The other side of the story is the pointer chasing in the page
	 * table walking code (when walking the page table without locking;
	 * ie. most of the time). Fortunately, these data accesses consist
	 * of a chain of data-dependent loads, meaning most CPUs (alpha
	 * being the notable exception) will already guarantee loads are
	 * seen in-order. See the alpha page table accessors for the
	 * smp_read_barrier_depends() barriers in page table walking code.
	 */
	smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

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	spin_lock(&mm->page_table_lock);
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	wait_split_huge_page = 0;
	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
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		mm->nr_ptes++;
		pmd_populate(mm, pmd, new);
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		new = NULL;
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	} else if (unlikely(pmd_trans_splitting(*pmd)))
		wait_split_huge_page = 1;
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	spin_unlock(&mm->page_table_lock);
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	if (new)
		pte_free(mm, new);
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	if (wait_split_huge_page)
		wait_split_huge_page(vma->anon_vma, pmd);
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	return 0;
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}

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int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
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{
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	pte_t *new = pte_alloc_one_kernel(&init_mm, address);
	if (!new)
		return -ENOMEM;

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	smp_wmb(); /* See comment in __pte_alloc */

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	spin_lock(&init_mm.page_table_lock);
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	if (likely(pmd_none(*pmd))) {	/* Has another populated it ? */
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		pmd_populate_kernel(&init_mm, pmd, new);
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		new = NULL;
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	} else
		VM_BUG_ON(pmd_trans_splitting(*pmd));
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	spin_unlock(&init_mm.page_table_lock);
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	if (new)
		pte_free_kernel(&init_mm, new);
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	return 0;
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}

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static inline void init_rss_vec(int *rss)
{
	memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
}

static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
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{
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	int i;

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	if (current->mm == mm)
		sync_mm_rss(current, mm);
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	for (i = 0; i < NR_MM_COUNTERS; i++)
		if (rss[i])
			add_mm_counter(mm, i, rss[i]);
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}

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/*
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 * This function is called to print an error when a bad pte
 * is found. For example, we might have a PFN-mapped pte in
 * a region that doesn't allow it.
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 *
 * The calling function must still handle the error.
 */
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static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
			  pte_t pte, struct page *page)
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{
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	pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
	pud_t *pud = pud_offset(pgd, addr);
	pmd_t *pmd = pmd_offset(pud, addr);
	struct address_space *mapping;
	pgoff_t index;
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	static unsigned long resume;
	static unsigned long nr_shown;
	static unsigned long nr_unshown;

	/*
	 * Allow a burst of 60 reports, then keep quiet for that minute;
	 * or allow a steady drip of one report per second.
	 */
	if (nr_shown == 60) {
		if (time_before(jiffies, resume)) {
			nr_unshown++;
			return;
		}
		if (nr_unshown) {
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			printk(KERN_ALERT
				"BUG: Bad page map: %lu messages suppressed\n",
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				nr_unshown);
			nr_unshown = 0;
		}
		nr_shown = 0;
	}
	if (nr_shown++ == 0)
		resume = jiffies + 60 * HZ;
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	mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
	index = linear_page_index(vma, addr);

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	printk(KERN_ALERT
		"BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
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		current->comm,
		(long long)pte_val(pte), (long long)pmd_val(*pmd));
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	if (page)
		dump_page(page);
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	printk(KERN_ALERT
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		"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
		(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
	/*
	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
	 */
	if (vma->vm_ops)
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		print_symbol(KERN_ALERT "vma->vm_ops->fault: %s\n",
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				(unsigned long)vma->vm_ops->fault);
	if (vma->vm_file && vma->vm_file->f_op)
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		print_symbol(KERN_ALERT "vma->vm_file->f_op->mmap: %s\n",
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				(unsigned long)vma->vm_file->f_op->mmap);
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	dump_stack();
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	add_taint(TAINT_BAD_PAGE);
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}

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static inline int is_cow_mapping(unsigned int flags)
{
	return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}

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#ifndef is_zero_pfn
static inline int is_zero_pfn(unsigned long pfn)
{
	return pfn == zero_pfn;
}
#endif

#ifndef my_zero_pfn
static inline unsigned long my_zero_pfn(unsigned long addr)
{
	return zero_pfn;
}
#endif

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/*
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 * vm_normal_page -- This function gets the "struct page" associated with a pte.
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 *
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 * "Special" mappings do not wish to be associated with a "struct page" (either
 * it doesn't exist, or it exists but they don't want to touch it). In this
 * case, NULL is returned here. "Normal" mappings do have a struct page.
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 *
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 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
 * pte bit, in which case this function is trivial. Secondly, an architecture
 * may not have a spare pte bit, which requires a more complicated scheme,
 * described below.
 *
 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
 * special mapping (even if there are underlying and valid "struct pages").
 * COWed pages of a VM_PFNMAP are always normal.
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 *
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 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
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 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
 * mapping will always honor the rule
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 *
 *	pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
 *
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 * And for normal mappings this is false.
 *
 * This restricts such mappings to be a linear translation from virtual address
 * to pfn. To get around this restriction, we allow arbitrary mappings so long
 * as the vma is not a COW mapping; in that case, we know that all ptes are
 * special (because none can have been COWed).
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 *
 *
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586
 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
J
Jared Hulbert 已提交
587 588 589 590 591 592 593 594 595
 *
 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
 * page" backing, however the difference is that _all_ pages with a struct
 * page (that is, those where pfn_valid is true) are refcounted and considered
 * normal pages by the VM. The disadvantage is that pages are refcounted
 * (which can be slower and simply not an option for some PFNMAP users). The
 * advantage is that we don't have to follow the strict linearity rule of
 * PFNMAP mappings in order to support COWable mappings.
 *
H
Hugh Dickins 已提交
596
 */
N
Nick Piggin 已提交
597 598 599 600 601 602 603
#ifdef __HAVE_ARCH_PTE_SPECIAL
# define HAVE_PTE_SPECIAL 1
#else
# define HAVE_PTE_SPECIAL 0
#endif
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
				pte_t pte)
H
Hugh Dickins 已提交
604
{
605
	unsigned long pfn = pte_pfn(pte);
N
Nick Piggin 已提交
606 607

	if (HAVE_PTE_SPECIAL) {
608 609
		if (likely(!pte_special(pte)))
			goto check_pfn;
H
Hugh Dickins 已提交
610 611
		if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
			return NULL;
H
Hugh Dickins 已提交
612
		if (!is_zero_pfn(pfn))
613
			print_bad_pte(vma, addr, pte, NULL);
N
Nick Piggin 已提交
614 615 616 617 618
		return NULL;
	}

	/* !HAVE_PTE_SPECIAL case follows: */

J
Jared Hulbert 已提交
619 620 621 622 623 624
	if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
		if (vma->vm_flags & VM_MIXEDMAP) {
			if (!pfn_valid(pfn))
				return NULL;
			goto out;
		} else {
N
Nick Piggin 已提交
625 626
			unsigned long off;
			off = (addr - vma->vm_start) >> PAGE_SHIFT;
J
Jared Hulbert 已提交
627 628 629 630 631
			if (pfn == vma->vm_pgoff + off)
				return NULL;
			if (!is_cow_mapping(vma->vm_flags))
				return NULL;
		}
632 633
	}

H
Hugh Dickins 已提交
634 635
	if (is_zero_pfn(pfn))
		return NULL;
636 637 638 639 640
check_pfn:
	if (unlikely(pfn > highest_memmap_pfn)) {
		print_bad_pte(vma, addr, pte, NULL);
		return NULL;
	}
641 642

	/*
N
Nick Piggin 已提交
643 644
	 * NOTE! We still have PageReserved() pages in the page tables.
	 * eg. VDSO mappings can cause them to exist.
645
	 */
J
Jared Hulbert 已提交
646
out:
647
	return pfn_to_page(pfn);
H
Hugh Dickins 已提交
648 649
}

L
Linus Torvalds 已提交
650 651 652 653 654 655
/*
 * copy one vm_area from one task to the other. Assumes the page tables
 * already present in the new task to be cleared in the whole range
 * covered by this vma.
 */

H
Hugh Dickins 已提交
656
static inline unsigned long
L
Linus Torvalds 已提交
657
copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
N
Nick Piggin 已提交
658
		pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
H
Hugh Dickins 已提交
659
		unsigned long addr, int *rss)
L
Linus Torvalds 已提交
660
{
N
Nick Piggin 已提交
661
	unsigned long vm_flags = vma->vm_flags;
L
Linus Torvalds 已提交
662 663 664 665 666 667
	pte_t pte = *src_pte;
	struct page *page;

	/* pte contains position in swap or file, so copy. */
	if (unlikely(!pte_present(pte))) {
		if (!pte_file(pte)) {
668 669
			swp_entry_t entry = pte_to_swp_entry(pte);

H
Hugh Dickins 已提交
670 671 672
			if (swap_duplicate(entry) < 0)
				return entry.val;

L
Linus Torvalds 已提交
673 674 675
			/* make sure dst_mm is on swapoff's mmlist. */
			if (unlikely(list_empty(&dst_mm->mmlist))) {
				spin_lock(&mmlist_lock);
676 677 678
				if (list_empty(&dst_mm->mmlist))
					list_add(&dst_mm->mmlist,
						 &src_mm->mmlist);
L
Linus Torvalds 已提交
679 680
				spin_unlock(&mmlist_lock);
			}
K
KAMEZAWA Hiroyuki 已提交
681 682 683
			if (likely(!non_swap_entry(entry)))
				rss[MM_SWAPENTS]++;
			else if (is_write_migration_entry(entry) &&
684 685 686 687 688 689 690 691 692
					is_cow_mapping(vm_flags)) {
				/*
				 * COW mappings require pages in both parent
				 * and child to be set to read.
				 */
				make_migration_entry_read(&entry);
				pte = swp_entry_to_pte(entry);
				set_pte_at(src_mm, addr, src_pte, pte);
			}
L
Linus Torvalds 已提交
693
		}
694
		goto out_set_pte;
L
Linus Torvalds 已提交
695 696 697 698 699 700
	}

	/*
	 * If it's a COW mapping, write protect it both
	 * in the parent and the child
	 */
701
	if (is_cow_mapping(vm_flags)) {
L
Linus Torvalds 已提交
702
		ptep_set_wrprotect(src_mm, addr, src_pte);
703
		pte = pte_wrprotect(pte);
L
Linus Torvalds 已提交
704 705 706 707 708 709 710 711 712
	}

	/*
	 * If it's a shared mapping, mark it clean in
	 * the child
	 */
	if (vm_flags & VM_SHARED)
		pte = pte_mkclean(pte);
	pte = pte_mkold(pte);
713 714 715 716

	page = vm_normal_page(vma, addr, pte);
	if (page) {
		get_page(page);
H
Hugh Dickins 已提交
717
		page_dup_rmap(page);
K
KAMEZAWA Hiroyuki 已提交
718 719 720 721
		if (PageAnon(page))
			rss[MM_ANONPAGES]++;
		else
			rss[MM_FILEPAGES]++;
722
	}
723 724 725

out_set_pte:
	set_pte_at(dst_mm, addr, dst_pte, pte);
H
Hugh Dickins 已提交
726
	return 0;
L
Linus Torvalds 已提交
727 728
}

729 730 731
int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		   pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
		   unsigned long addr, unsigned long end)
L
Linus Torvalds 已提交
732
{
733
	pte_t *orig_src_pte, *orig_dst_pte;
L
Linus Torvalds 已提交
734
	pte_t *src_pte, *dst_pte;
H
Hugh Dickins 已提交
735
	spinlock_t *src_ptl, *dst_ptl;
736
	int progress = 0;
K
KAMEZAWA Hiroyuki 已提交
737
	int rss[NR_MM_COUNTERS];
H
Hugh Dickins 已提交
738
	swp_entry_t entry = (swp_entry_t){0};
L
Linus Torvalds 已提交
739 740

again:
K
KAMEZAWA Hiroyuki 已提交
741 742
	init_rss_vec(rss);

H
Hugh Dickins 已提交
743
	dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
L
Linus Torvalds 已提交
744 745
	if (!dst_pte)
		return -ENOMEM;
P
Peter Zijlstra 已提交
746
	src_pte = pte_offset_map(src_pmd, addr);
H
Hugh Dickins 已提交
747
	src_ptl = pte_lockptr(src_mm, src_pmd);
I
Ingo Molnar 已提交
748
	spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
749 750
	orig_src_pte = src_pte;
	orig_dst_pte = dst_pte;
751
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
752 753 754 755 756 757

	do {
		/*
		 * We are holding two locks at this point - either of them
		 * could generate latencies in another task on another CPU.
		 */
758 759 760
		if (progress >= 32) {
			progress = 0;
			if (need_resched() ||
N
Nick Piggin 已提交
761
			    spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
762 763
				break;
		}
L
Linus Torvalds 已提交
764 765 766 767
		if (pte_none(*src_pte)) {
			progress++;
			continue;
		}
H
Hugh Dickins 已提交
768 769 770 771
		entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
							vma, addr, rss);
		if (entry.val)
			break;
L
Linus Torvalds 已提交
772 773 774
		progress += 8;
	} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);

775
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
776
	spin_unlock(src_ptl);
P
Peter Zijlstra 已提交
777
	pte_unmap(orig_src_pte);
K
KAMEZAWA Hiroyuki 已提交
778
	add_mm_rss_vec(dst_mm, rss);
779
	pte_unmap_unlock(orig_dst_pte, dst_ptl);
H
Hugh Dickins 已提交
780
	cond_resched();
H
Hugh Dickins 已提交
781 782 783 784 785 786

	if (entry.val) {
		if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
			return -ENOMEM;
		progress = 0;
	}
L
Linus Torvalds 已提交
787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804
	if (addr != end)
		goto again;
	return 0;
}

static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pmd_t *src_pmd, *dst_pmd;
	unsigned long next;

	dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
	if (!dst_pmd)
		return -ENOMEM;
	src_pmd = pmd_offset(src_pud, addr);
	do {
		next = pmd_addr_end(addr, end);
805 806
		if (pmd_trans_huge(*src_pmd)) {
			int err;
807
			VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
808 809 810 811 812 813 814 815
			err = copy_huge_pmd(dst_mm, src_mm,
					    dst_pmd, src_pmd, addr, vma);
			if (err == -ENOMEM)
				return -ENOMEM;
			if (!err)
				continue;
			/* fall through */
		}
L
Linus Torvalds 已提交
816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853
		if (pmd_none_or_clear_bad(src_pmd))
			continue;
		if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pmd++, src_pmd++, addr = next, addr != end);
	return 0;
}

static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
		unsigned long addr, unsigned long end)
{
	pud_t *src_pud, *dst_pud;
	unsigned long next;

	dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
	if (!dst_pud)
		return -ENOMEM;
	src_pud = pud_offset(src_pgd, addr);
	do {
		next = pud_addr_end(addr, end);
		if (pud_none_or_clear_bad(src_pud))
			continue;
		if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
						vma, addr, next))
			return -ENOMEM;
	} while (dst_pud++, src_pud++, addr = next, addr != end);
	return 0;
}

int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
		struct vm_area_struct *vma)
{
	pgd_t *src_pgd, *dst_pgd;
	unsigned long next;
	unsigned long addr = vma->vm_start;
	unsigned long end = vma->vm_end;
A
Andrea Arcangeli 已提交
854
	int ret;
L
Linus Torvalds 已提交
855

856 857 858 859 860 861
	/*
	 * Don't copy ptes where a page fault will fill them correctly.
	 * Fork becomes much lighter when there are big shared or private
	 * readonly mappings. The tradeoff is that copy_page_range is more
	 * efficient than faulting.
	 */
862
	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {
863 864 865 866
		if (!vma->anon_vma)
			return 0;
	}

L
Linus Torvalds 已提交
867 868 869
	if (is_vm_hugetlb_page(vma))
		return copy_hugetlb_page_range(dst_mm, src_mm, vma);

870
	if (unlikely(is_pfn_mapping(vma))) {
871 872 873 874 875 876 877 878 879
		/*
		 * We do not free on error cases below as remove_vma
		 * gets called on error from higher level routine
		 */
		ret = track_pfn_vma_copy(vma);
		if (ret)
			return ret;
	}

A
Andrea Arcangeli 已提交
880 881 882 883 884 885 886 887 888 889
	/*
	 * We need to invalidate the secondary MMU mappings only when
	 * there could be a permission downgrade on the ptes of the
	 * parent mm. And a permission downgrade will only happen if
	 * is_cow_mapping() returns true.
	 */
	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_start(src_mm, addr, end);

	ret = 0;
L
Linus Torvalds 已提交
890 891 892 893 894 895
	dst_pgd = pgd_offset(dst_mm, addr);
	src_pgd = pgd_offset(src_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		if (pgd_none_or_clear_bad(src_pgd))
			continue;
A
Andrea Arcangeli 已提交
896 897 898 899 900
		if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
					    vma, addr, next))) {
			ret = -ENOMEM;
			break;
		}
L
Linus Torvalds 已提交
901
	} while (dst_pgd++, src_pgd++, addr = next, addr != end);
A
Andrea Arcangeli 已提交
902 903 904 905 906

	if (is_cow_mapping(vma->vm_flags))
		mmu_notifier_invalidate_range_end(src_mm,
						  vma->vm_start, end);
	return ret;
L
Linus Torvalds 已提交
907 908
}

909
static unsigned long zap_pte_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
910
				struct vm_area_struct *vma, pmd_t *pmd,
L
Linus Torvalds 已提交
911
				unsigned long addr, unsigned long end,
912
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
913
{
N
Nick Piggin 已提交
914
	struct mm_struct *mm = tlb->mm;
L
Linus Torvalds 已提交
915
	pte_t *pte;
916
	spinlock_t *ptl;
K
KAMEZAWA Hiroyuki 已提交
917 918 919
	int rss[NR_MM_COUNTERS];

	init_rss_vec(rss);
L
Linus Torvalds 已提交
920

921
	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
922
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
923 924
	do {
		pte_t ptent = *pte;
925 926
		if (pte_none(ptent)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
927
			continue;
928
		}
929 930 931

		(*zap_work) -= PAGE_SIZE;

L
Linus Torvalds 已提交
932
		if (pte_present(ptent)) {
H
Hugh Dickins 已提交
933
			struct page *page;
934

935
			page = vm_normal_page(vma, addr, ptent);
L
Linus Torvalds 已提交
936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953
			if (unlikely(details) && page) {
				/*
				 * unmap_shared_mapping_pages() wants to
				 * invalidate cache without truncating:
				 * unmap shared but keep private pages.
				 */
				if (details->check_mapping &&
				    details->check_mapping != page->mapping)
					continue;
				/*
				 * Each page->index must be checked when
				 * invalidating or truncating nonlinear.
				 */
				if (details->nonlinear_vma &&
				    (page->index < details->first_index ||
				     page->index > details->last_index))
					continue;
			}
N
Nick Piggin 已提交
954
			ptent = ptep_get_and_clear_full(mm, addr, pte,
955
							tlb->fullmm);
L
Linus Torvalds 已提交
956 957 958 959 960 961
			tlb_remove_tlb_entry(tlb, pte, addr);
			if (unlikely(!page))
				continue;
			if (unlikely(details) && details->nonlinear_vma
			    && linear_page_index(details->nonlinear_vma,
						addr) != page->index)
N
Nick Piggin 已提交
962
				set_pte_at(mm, addr, pte,
L
Linus Torvalds 已提交
963 964
					   pgoff_to_pte(page->index));
			if (PageAnon(page))
K
KAMEZAWA Hiroyuki 已提交
965
				rss[MM_ANONPAGES]--;
966 967 968
			else {
				if (pte_dirty(ptent))
					set_page_dirty(page);
969 970
				if (pte_young(ptent) &&
				    likely(!VM_SequentialReadHint(vma)))
971
					mark_page_accessed(page);
K
KAMEZAWA Hiroyuki 已提交
972
				rss[MM_FILEPAGES]--;
973
			}
974
			page_remove_rmap(page);
975 976
			if (unlikely(page_mapcount(page) < 0))
				print_bad_pte(vma, addr, ptent, page);
L
Linus Torvalds 已提交
977 978 979 980 981 982 983 984 985
			tlb_remove_page(tlb, page);
			continue;
		}
		/*
		 * If details->check_mapping, we leave swap entries;
		 * if details->nonlinear_vma, we leave file entries.
		 */
		if (unlikely(details))
			continue;
986 987 988
		if (pte_file(ptent)) {
			if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
				print_bad_pte(vma, addr, ptent, NULL);
K
KAMEZAWA Hiroyuki 已提交
989 990 991 992 993 994 995 996
		} else {
			swp_entry_t entry = pte_to_swp_entry(ptent);

			if (!non_swap_entry(entry))
				rss[MM_SWAPENTS]--;
			if (unlikely(!free_swap_and_cache(entry)))
				print_bad_pte(vma, addr, ptent, NULL);
		}
997
		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
998
	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
999

K
KAMEZAWA Hiroyuki 已提交
1000
	add_mm_rss_vec(mm, rss);
1001
	arch_leave_lazy_mmu_mode();
1002
	pte_unmap_unlock(pte - 1, ptl);
1003 1004

	return addr;
L
Linus Torvalds 已提交
1005 1006
}

1007
static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1008
				struct vm_area_struct *vma, pud_t *pud,
L
Linus Torvalds 已提交
1009
				unsigned long addr, unsigned long end,
1010
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
1011 1012 1013 1014 1015 1016 1017
{
	pmd_t *pmd;
	unsigned long next;

	pmd = pmd_offset(pud, addr);
	do {
		next = pmd_addr_end(addr, end);
1018
		if (pmd_trans_huge(*pmd)) {
1019 1020
			if (next-addr != HPAGE_PMD_SIZE) {
				VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
1021
				split_huge_page_pmd(vma->vm_mm, pmd);
1022
			} else if (zap_huge_pmd(tlb, vma, pmd)) {
1023 1024 1025 1026 1027
				(*zap_work)--;
				continue;
			}
			/* fall through */
		}
1028 1029
		if (pmd_none_or_clear_bad(pmd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1030
			continue;
1031 1032 1033 1034 1035 1036
		}
		next = zap_pte_range(tlb, vma, pmd, addr, next,
						zap_work, details);
	} while (pmd++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
1037 1038
}

1039
static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
N
Nick Piggin 已提交
1040
				struct vm_area_struct *vma, pgd_t *pgd,
L
Linus Torvalds 已提交
1041
				unsigned long addr, unsigned long end,
1042
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
1043 1044 1045 1046 1047 1048 1049
{
	pud_t *pud;
	unsigned long next;

	pud = pud_offset(pgd, addr);
	do {
		next = pud_addr_end(addr, end);
1050 1051
		if (pud_none_or_clear_bad(pud)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1052
			continue;
1053 1054 1055 1056 1057 1058
		}
		next = zap_pmd_range(tlb, vma, pud, addr, next,
						zap_work, details);
	} while (pud++, addr = next, (addr != end && *zap_work > 0));

	return addr;
L
Linus Torvalds 已提交
1059 1060
}

1061 1062
static unsigned long unmap_page_range(struct mmu_gather *tlb,
				struct vm_area_struct *vma,
L
Linus Torvalds 已提交
1063
				unsigned long addr, unsigned long end,
1064
				long *zap_work, struct zap_details *details)
L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070 1071 1072
{
	pgd_t *pgd;
	unsigned long next;

	if (details && !details->check_mapping && !details->nonlinear_vma)
		details = NULL;

	BUG_ON(addr >= end);
1073
	mem_cgroup_uncharge_start();
L
Linus Torvalds 已提交
1074 1075 1076 1077
	tlb_start_vma(tlb, vma);
	pgd = pgd_offset(vma->vm_mm, addr);
	do {
		next = pgd_addr_end(addr, end);
1078 1079
		if (pgd_none_or_clear_bad(pgd)) {
			(*zap_work)--;
L
Linus Torvalds 已提交
1080
			continue;
1081 1082 1083 1084
		}
		next = zap_pud_range(tlb, vma, pgd, addr, next,
						zap_work, details);
	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
L
Linus Torvalds 已提交
1085
	tlb_end_vma(tlb, vma);
1086
	mem_cgroup_uncharge_end();
1087 1088

	return addr;
L
Linus Torvalds 已提交
1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106
}

#ifdef CONFIG_PREEMPT
# define ZAP_BLOCK_SIZE	(8 * PAGE_SIZE)
#else
/* No preempt: go for improved straight-line efficiency */
# define ZAP_BLOCK_SIZE	(1024 * PAGE_SIZE)
#endif

/**
 * unmap_vmas - unmap a range of memory covered by a list of vma's
 * @tlbp: address of the caller's struct mmu_gather
 * @vma: the starting vma
 * @start_addr: virtual address at which to start unmapping
 * @end_addr: virtual address at which to end unmapping
 * @nr_accounted: Place number of unmapped pages in vm-accountable vma's here
 * @details: details of nonlinear truncation or shared cache invalidation
 *
1107
 * Returns the end address of the unmapping (restart addr if interrupted).
L
Linus Torvalds 已提交
1108
 *
1109
 * Unmap all pages in the vma list.
L
Linus Torvalds 已提交
1110
 *
1111 1112
 * We aim to not hold locks for too long (for scheduling latency reasons).
 * So zap pages in ZAP_BLOCK_SIZE bytecounts.  This means we need to
L
Linus Torvalds 已提交
1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123
 * return the ending mmu_gather to the caller.
 *
 * Only addresses between `start' and `end' will be unmapped.
 *
 * The VMA list must be sorted in ascending virtual address order.
 *
 * unmap_vmas() assumes that the caller will flush the whole unmapped address
 * range after unmap_vmas() returns.  So the only responsibility here is to
 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
 * drops the lock and schedules.
 */
1124
unsigned long unmap_vmas(struct mmu_gather **tlbp,
L
Linus Torvalds 已提交
1125 1126 1127 1128
		struct vm_area_struct *vma, unsigned long start_addr,
		unsigned long end_addr, unsigned long *nr_accounted,
		struct zap_details *details)
{
1129
	long zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1130 1131
	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
	int tlb_start_valid = 0;
1132
	unsigned long start = start_addr;
L
Linus Torvalds 已提交
1133
	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
1134
	int fullmm = (*tlbp)->fullmm;
A
Andrea Arcangeli 已提交
1135
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1136

A
Andrea Arcangeli 已提交
1137
	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
L
Linus Torvalds 已提交
1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150
	for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next) {
		unsigned long end;

		start = max(vma->vm_start, start_addr);
		if (start >= vma->vm_end)
			continue;
		end = min(vma->vm_end, end_addr);
		if (end <= vma->vm_start)
			continue;

		if (vma->vm_flags & VM_ACCOUNT)
			*nr_accounted += (end - start) >> PAGE_SHIFT;

1151
		if (unlikely(is_pfn_mapping(vma)))
1152 1153
			untrack_pfn_vma(vma, 0, 0);

L
Linus Torvalds 已提交
1154 1155 1156 1157 1158 1159
		while (start != end) {
			if (!tlb_start_valid) {
				tlb_start = start;
				tlb_start_valid = 1;
			}

1160
			if (unlikely(is_vm_hugetlb_page(vma))) {
1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174
				/*
				 * It is undesirable to test vma->vm_file as it
				 * should be non-null for valid hugetlb area.
				 * However, vm_file will be NULL in the error
				 * cleanup path of do_mmap_pgoff. When
				 * hugetlbfs ->mmap method fails,
				 * do_mmap_pgoff() nullifies vma->vm_file
				 * before calling this function to clean up.
				 * Since no pte has actually been setup, it is
				 * safe to do nothing in this case.
				 */
				if (vma->vm_file) {
					unmap_hugepage_range(vma, start, end, NULL);
					zap_work -= (end - start) /
1175
					pages_per_huge_page(hstate_vma(vma));
1176 1177
				}

1178 1179 1180 1181 1182 1183 1184 1185
				start = end;
			} else
				start = unmap_page_range(*tlbp, vma,
						start, end, &zap_work, details);

			if (zap_work > 0) {
				BUG_ON(start != end);
				break;
L
Linus Torvalds 已提交
1186 1187 1188 1189 1190
			}

			tlb_finish_mmu(*tlbp, tlb_start, start);

			if (need_resched() ||
N
Nick Piggin 已提交
1191
				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
L
Linus Torvalds 已提交
1192
				if (i_mmap_lock) {
1193
					*tlbp = NULL;
L
Linus Torvalds 已提交
1194 1195 1196 1197 1198
					goto out;
				}
				cond_resched();
			}

1199
			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
L
Linus Torvalds 已提交
1200
			tlb_start_valid = 0;
1201
			zap_work = ZAP_BLOCK_SIZE;
L
Linus Torvalds 已提交
1202 1203 1204
		}
	}
out:
A
Andrea Arcangeli 已提交
1205
	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1206
	return start;	/* which is now the end (or restart) address */
L
Linus Torvalds 已提交
1207 1208 1209 1210 1211 1212 1213 1214 1215
}

/**
 * zap_page_range - remove user pages in a given range
 * @vma: vm_area_struct holding the applicable pages
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 * @details: details of nonlinear truncation or shared cache invalidation
 */
1216
unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
L
Linus Torvalds 已提交
1217 1218 1219 1220 1221 1222 1223 1224 1225
		unsigned long size, struct zap_details *details)
{
	struct mm_struct *mm = vma->vm_mm;
	struct mmu_gather *tlb;
	unsigned long end = address + size;
	unsigned long nr_accounted = 0;

	lru_add_drain();
	tlb = tlb_gather_mmu(mm, 0);
1226
	update_hiwater_rss(mm);
1227 1228 1229
	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
	if (tlb)
		tlb_finish_mmu(tlb, address, end);
1230
	return end;
L
Linus Torvalds 已提交
1231 1232
}

1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255
/**
 * zap_vma_ptes - remove ptes mapping the vma
 * @vma: vm_area_struct holding ptes to be zapped
 * @address: starting address of pages to zap
 * @size: number of bytes to zap
 *
 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
 *
 * The entire address range must be fully contained within the vma.
 *
 * Returns 0 if successful.
 */
int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
		unsigned long size)
{
	if (address < vma->vm_start || address + size > vma->vm_end ||
	    		!(vma->vm_flags & VM_PFNMAP))
		return -1;
	zap_page_range(vma, address, size, NULL);
	return 0;
}
EXPORT_SYMBOL_GPL(zap_vma_ptes);

J
Johannes Weiner 已提交
1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266
/**
 * follow_page - look up a page descriptor from a user-virtual address
 * @vma: vm_area_struct mapping @address
 * @address: virtual address to look up
 * @flags: flags modifying lookup behaviour
 *
 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
 *
 * Returns the mapped (struct page *), %NULL if no mapping exists, or
 * an error pointer if there is a mapping to something not represented
 * by a page descriptor (see also vm_normal_page()).
L
Linus Torvalds 已提交
1267
 */
1268
struct page *follow_page(struct vm_area_struct *vma, unsigned long address,
1269
			unsigned int flags)
L
Linus Torvalds 已提交
1270 1271 1272 1273 1274
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep, pte;
1275
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1276
	struct page *page;
1277
	struct mm_struct *mm = vma->vm_mm;
L
Linus Torvalds 已提交
1278

1279 1280 1281 1282 1283
	page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
	if (!IS_ERR(page)) {
		BUG_ON(flags & FOLL_GET);
		goto out;
	}
L
Linus Torvalds 已提交
1284

1285
	page = NULL;
L
Linus Torvalds 已提交
1286 1287
	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1288
		goto no_page_table;
L
Linus Torvalds 已提交
1289 1290

	pud = pud_offset(pgd, address);
A
Andi Kleen 已提交
1291
	if (pud_none(*pud))
1292
		goto no_page_table;
1293
	if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
A
Andi Kleen 已提交
1294 1295 1296 1297 1298 1299 1300
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
		goto out;
	}
	if (unlikely(pud_bad(*pud)))
		goto no_page_table;

L
Linus Torvalds 已提交
1301
	pmd = pmd_offset(pud, address);
1302
	if (pmd_none(*pmd))
1303
		goto no_page_table;
1304
	if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1305 1306
		BUG_ON(flags & FOLL_GET);
		page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
L
Linus Torvalds 已提交
1307
		goto out;
1308
	}
1309
	if (pmd_trans_huge(*pmd)) {
1310 1311 1312 1313
		if (flags & FOLL_SPLIT) {
			split_huge_page_pmd(mm, pmd);
			goto split_fallthrough;
		}
1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328
		spin_lock(&mm->page_table_lock);
		if (likely(pmd_trans_huge(*pmd))) {
			if (unlikely(pmd_trans_splitting(*pmd))) {
				spin_unlock(&mm->page_table_lock);
				wait_split_huge_page(vma->anon_vma, pmd);
			} else {
				page = follow_trans_huge_pmd(mm, address,
							     pmd, flags);
				spin_unlock(&mm->page_table_lock);
				goto out;
			}
		} else
			spin_unlock(&mm->page_table_lock);
		/* fall through */
	}
1329
split_fallthrough:
1330 1331 1332
	if (unlikely(pmd_bad(*pmd)))
		goto no_page_table;

1333
	ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
1334 1335

	pte = *ptep;
1336
	if (!pte_present(pte))
1337
		goto no_page;
1338 1339
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;
H
Hugh Dickins 已提交
1340

1341
	page = vm_normal_page(vma, address, pte);
H
Hugh Dickins 已提交
1342 1343
	if (unlikely(!page)) {
		if ((flags & FOLL_DUMP) ||
H
Hugh Dickins 已提交
1344
		    !is_zero_pfn(pte_pfn(pte)))
H
Hugh Dickins 已提交
1345 1346 1347
			goto bad_page;
		page = pte_page(pte);
	}
L
Linus Torvalds 已提交
1348

1349 1350 1351 1352 1353 1354
	if (flags & FOLL_GET)
		get_page(page);
	if (flags & FOLL_TOUCH) {
		if ((flags & FOLL_WRITE) &&
		    !pte_dirty(pte) && !PageDirty(page))
			set_page_dirty(page);
1355 1356 1357 1358 1359
		/*
		 * pte_mkyoung() would be more correct here, but atomic care
		 * is needed to avoid losing the dirty bit: it is easier to use
		 * mark_page_accessed().
		 */
1360 1361
		mark_page_accessed(page);
	}
1362
	if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383
		/*
		 * The preliminary mapping check is mainly to avoid the
		 * pointless overhead of lock_page on the ZERO_PAGE
		 * which might bounce very badly if there is contention.
		 *
		 * If the page is already locked, we don't need to
		 * handle it now - vmscan will handle it later if and
		 * when it attempts to reclaim the page.
		 */
		if (page->mapping && trylock_page(page)) {
			lru_add_drain();  /* push cached pages to LRU */
			/*
			 * Because we lock page here and migration is
			 * blocked by the pte's page reference, we need
			 * only check for file-cache page truncation.
			 */
			if (page->mapping)
				mlock_vma_page(page);
			unlock_page(page);
		}
	}
1384 1385
unlock:
	pte_unmap_unlock(ptep, ptl);
L
Linus Torvalds 已提交
1386
out:
1387
	return page;
L
Linus Torvalds 已提交
1388

1389 1390 1391 1392 1393 1394 1395 1396
bad_page:
	pte_unmap_unlock(ptep, ptl);
	return ERR_PTR(-EFAULT);

no_page:
	pte_unmap_unlock(ptep, ptl);
	if (!pte_none(pte))
		return page;
H
Hugh Dickins 已提交
1397

1398 1399 1400
no_page_table:
	/*
	 * When core dumping an enormous anonymous area that nobody
H
Hugh Dickins 已提交
1401 1402 1403 1404 1405
	 * has touched so far, we don't want to allocate unnecessary pages or
	 * page tables.  Return error instead of NULL to skip handle_mm_fault,
	 * then get_dump_page() will return NULL to leave a hole in the dump.
	 * But we can only make this optimization where a hole would surely
	 * be zero-filled if handle_mm_fault() actually did handle it.
1406
	 */
H
Hugh Dickins 已提交
1407 1408 1409
	if ((flags & FOLL_DUMP) &&
	    (!vma->vm_ops || !vma->vm_ops->fault))
		return ERR_PTR(-EFAULT);
1410
	return page;
L
Linus Torvalds 已提交
1411 1412
}

1413 1414
static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
{
1415 1416
	return stack_guard_page_start(vma, addr) ||
	       stack_guard_page_end(vma, addr+PAGE_SIZE);
1417 1418
}

H
Huang Ying 已提交
1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467
/**
 * __get_user_pages() - pin user pages in memory
 * @tsk:	task_struct of target task
 * @mm:		mm_struct of target mm
 * @start:	starting user address
 * @nr_pages:	number of pages from start to pin
 * @gup_flags:	flags modifying pin behaviour
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 * @nonblocking: whether waiting for disk IO or mmap_sem contention
 *
 * Returns number of pages pinned. This may be fewer than the number
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * __get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * __get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
 * appropriate) must be called after the page is finished with, and
 * before put_page is called.
 *
 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
 * or mmap_sem contention, and if waiting is needed to pin all pages,
 * *@nonblocking will be set to 0.
 *
 * In most cases, get_user_pages or get_user_pages_fast should be used
 * instead of __get_user_pages. __get_user_pages should be used only if
 * you need some special @gup_flags.
 */
N
Nick Piggin 已提交
1468
int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
H
Hugh Dickins 已提交
1469
		     unsigned long start, int nr_pages, unsigned int gup_flags,
1470 1471
		     struct page **pages, struct vm_area_struct **vmas,
		     int *nonblocking)
L
Linus Torvalds 已提交
1472 1473
{
	int i;
H
Hugh Dickins 已提交
1474
	unsigned long vm_flags;
L
Linus Torvalds 已提交
1475

1476
	if (nr_pages <= 0)
1477
		return 0;
H
Hugh Dickins 已提交
1478 1479 1480

	VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));

L
Linus Torvalds 已提交
1481 1482
	/* 
	 * Require read or write permissions.
H
Hugh Dickins 已提交
1483
	 * If FOLL_FORCE is set, we only require the "MAY" flags.
L
Linus Torvalds 已提交
1484
	 */
H
Hugh Dickins 已提交
1485 1486 1487 1488
	vm_flags  = (gup_flags & FOLL_WRITE) ?
			(VM_WRITE | VM_MAYWRITE) : (VM_READ | VM_MAYREAD);
	vm_flags &= (gup_flags & FOLL_FORCE) ?
			(VM_MAYREAD | VM_MAYWRITE) : (VM_READ | VM_WRITE);
L
Linus Torvalds 已提交
1489 1490 1491
	i = 0;

	do {
1492
		struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1493 1494

		vma = find_extend_vma(mm, start);
1495
		if (!vma && in_gate_area(mm, start)) {
L
Linus Torvalds 已提交
1496 1497 1498 1499 1500
			unsigned long pg = start & PAGE_MASK;
			pgd_t *pgd;
			pud_t *pud;
			pmd_t *pmd;
			pte_t *pte;
N
Nick Piggin 已提交
1501 1502

			/* user gate pages are read-only */
H
Hugh Dickins 已提交
1503
			if (gup_flags & FOLL_WRITE)
L
Linus Torvalds 已提交
1504 1505 1506 1507 1508 1509 1510 1511 1512
				return i ? : -EFAULT;
			if (pg > TASK_SIZE)
				pgd = pgd_offset_k(pg);
			else
				pgd = pgd_offset_gate(mm, pg);
			BUG_ON(pgd_none(*pgd));
			pud = pud_offset(pgd, pg);
			BUG_ON(pud_none(*pud));
			pmd = pmd_offset(pud, pg);
1513 1514
			if (pmd_none(*pmd))
				return i ? : -EFAULT;
1515
			VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1516
			pte = pte_offset_map(pmd, pg);
1517 1518 1519 1520
			if (pte_none(*pte)) {
				pte_unmap(pte);
				return i ? : -EFAULT;
			}
1521
			vma = get_gate_vma(mm);
L
Linus Torvalds 已提交
1522
			if (pages) {
1523 1524
				struct page *page;

1525
				page = vm_normal_page(vma, start, *pte);
1526 1527 1528 1529 1530 1531 1532 1533 1534
				if (!page) {
					if (!(gup_flags & FOLL_DUMP) &&
					     is_zero_pfn(pte_pfn(*pte)))
						page = pte_page(*pte);
					else {
						pte_unmap(pte);
						return i ? : -EFAULT;
					}
				}
1535
				pages[i] = page;
1536
				get_page(page);
L
Linus Torvalds 已提交
1537 1538
			}
			pte_unmap(pte);
1539
			goto next_page;
L
Linus Torvalds 已提交
1540 1541
		}

N
Nick Piggin 已提交
1542 1543
		if (!vma ||
		    (vma->vm_flags & (VM_IO | VM_PFNMAP)) ||
H
Hugh Dickins 已提交
1544
		    !(vm_flags & vma->vm_flags))
L
Linus Torvalds 已提交
1545 1546
			return i ? : -EFAULT;

H
Hugh Dickins 已提交
1547 1548
		if (is_vm_hugetlb_page(vma)) {
			i = follow_hugetlb_page(mm, vma, pages, vmas,
H
Hugh Dickins 已提交
1549
					&start, &nr_pages, i, gup_flags);
H
Hugh Dickins 已提交
1550 1551
			continue;
		}
1552

L
Linus Torvalds 已提交
1553
		do {
1554
			struct page *page;
H
Hugh Dickins 已提交
1555
			unsigned int foll_flags = gup_flags;
L
Linus Torvalds 已提交
1556

1557
			/*
1558
			 * If we have a pending SIGKILL, don't keep faulting
H
Hugh Dickins 已提交
1559
			 * pages and potentially allocating memory.
1560
			 */
H
Hugh Dickins 已提交
1561
			if (unlikely(fatal_signal_pending(current)))
1562
				return i ? i : -ERESTARTSYS;
1563

1564
			cond_resched();
1565
			while (!(page = follow_page(vma, start, foll_flags))) {
1566
				int ret;
1567 1568
				unsigned int fault_flags = 0;

1569 1570 1571 1572 1573
				/* For mlock, just skip the stack guard page. */
				if (foll_flags & FOLL_MLOCK) {
					if (stack_guard_page(vma, start))
						goto next_page;
				}
1574 1575 1576 1577
				if (foll_flags & FOLL_WRITE)
					fault_flags |= FAULT_FLAG_WRITE;
				if (nonblocking)
					fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1578 1579
				if (foll_flags & FOLL_NOWAIT)
					fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1580

1581
				ret = handle_mm_fault(mm, vma, start,
1582
							fault_flags);
1583

N
Nick Piggin 已提交
1584 1585 1586
				if (ret & VM_FAULT_ERROR) {
					if (ret & VM_FAULT_OOM)
						return i ? i : -ENOMEM;
1587 1588 1589 1590 1591 1592 1593 1594 1595 1596
					if (ret & (VM_FAULT_HWPOISON |
						   VM_FAULT_HWPOISON_LARGE)) {
						if (i)
							return i;
						else if (gup_flags & FOLL_HWPOISON)
							return -EHWPOISON;
						else
							return -EFAULT;
					}
					if (ret & VM_FAULT_SIGBUS)
N
Nick Piggin 已提交
1597 1598 1599
						return i ? i : -EFAULT;
					BUG();
				}
1600 1601 1602 1603 1604 1605 1606

				if (tsk) {
					if (ret & VM_FAULT_MAJOR)
						tsk->maj_flt++;
					else
						tsk->min_flt++;
				}
N
Nick Piggin 已提交
1607

1608
				if (ret & VM_FAULT_RETRY) {
1609 1610
					if (nonblocking)
						*nonblocking = 0;
1611 1612 1613
					return i;
				}

1614
				/*
N
Nick Piggin 已提交
1615 1616 1617 1618
				 * The VM_FAULT_WRITE bit tells us that
				 * do_wp_page has broken COW when necessary,
				 * even if maybe_mkwrite decided not to set
				 * pte_write. We can thus safely do subsequent
1619 1620 1621 1622 1623 1624
				 * page lookups as if they were reads. But only
				 * do so when looping for pte_write is futile:
				 * in some cases userspace may also be wanting
				 * to write to the gotten user page, which a
				 * read fault here might prevent (a readonly
				 * page might get reCOWed by userspace write).
1625
				 */
1626 1627
				if ((ret & VM_FAULT_WRITE) &&
				    !(vma->vm_flags & VM_WRITE))
1628
					foll_flags &= ~FOLL_WRITE;
N
Nick Piggin 已提交
1629

1630
				cond_resched();
L
Linus Torvalds 已提交
1631
			}
1632 1633
			if (IS_ERR(page))
				return i ? i : PTR_ERR(page);
L
Linus Torvalds 已提交
1634
			if (pages) {
1635
				pages[i] = page;
1636

1637
				flush_anon_page(vma, page, start);
1638
				flush_dcache_page(page);
L
Linus Torvalds 已提交
1639
			}
1640
next_page:
L
Linus Torvalds 已提交
1641 1642 1643 1644
			if (vmas)
				vmas[i] = vma;
			i++;
			start += PAGE_SIZE;
1645 1646 1647
			nr_pages--;
		} while (nr_pages && start < vma->vm_end);
	} while (nr_pages);
L
Linus Torvalds 已提交
1648 1649
	return i;
}
H
Huang Ying 已提交
1650
EXPORT_SYMBOL(__get_user_pages);
N
Nick Piggin 已提交
1651

1652 1653
/**
 * get_user_pages() - pin user pages in memory
1654 1655
 * @tsk:	the task_struct to use for page fault accounting, or
 *		NULL if faults are not to be recorded.
1656 1657
 * @mm:		mm_struct of target mm
 * @start:	starting user address
1658
 * @nr_pages:	number of pages from start to pin
1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669
 * @write:	whether pages will be written to by the caller
 * @force:	whether to force write access even if user mapping is
 *		readonly. This will result in the page being COWed even
 *		in MAP_SHARED mappings. You do not want this.
 * @pages:	array that receives pointers to the pages pinned.
 *		Should be at least nr_pages long. Or NULL, if caller
 *		only intends to ensure the pages are faulted in.
 * @vmas:	array of pointers to vmas corresponding to each page.
 *		Or NULL if the caller does not require them.
 *
 * Returns number of pages pinned. This may be fewer than the number
1670
 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702
 * were pinned, returns -errno. Each page returned must be released
 * with a put_page() call when it is finished with. vmas will only
 * remain valid while mmap_sem is held.
 *
 * Must be called with mmap_sem held for read or write.
 *
 * get_user_pages walks a process's page tables and takes a reference to
 * each struct page that each user address corresponds to at a given
 * instant. That is, it takes the page that would be accessed if a user
 * thread accesses the given user virtual address at that instant.
 *
 * This does not guarantee that the page exists in the user mappings when
 * get_user_pages returns, and there may even be a completely different
 * page there in some cases (eg. if mmapped pagecache has been invalidated
 * and subsequently re faulted). However it does guarantee that the page
 * won't be freed completely. And mostly callers simply care that the page
 * contains data that was valid *at some point in time*. Typically, an IO
 * or similar operation cannot guarantee anything stronger anyway because
 * locks can't be held over the syscall boundary.
 *
 * If write=0, the page must not be written to. If the page is written to,
 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
 * after the page is finished with, and before put_page is called.
 *
 * get_user_pages is typically used for fewer-copy IO operations, to get a
 * handle on the memory by some means other than accesses via the user virtual
 * addresses. The pages may be submitted for DMA to devices or accessed via
 * their kernel linear mapping (via the kmap APIs). Care should be taken to
 * use the correct cache flushing APIs.
 *
 * See also get_user_pages_fast, for performance critical applications.
 */
N
Nick Piggin 已提交
1703
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1704
		unsigned long start, int nr_pages, int write, int force,
N
Nick Piggin 已提交
1705 1706
		struct page **pages, struct vm_area_struct **vmas)
{
H
Hugh Dickins 已提交
1707
	int flags = FOLL_TOUCH;
N
Nick Piggin 已提交
1708

H
Hugh Dickins 已提交
1709 1710
	if (pages)
		flags |= FOLL_GET;
N
Nick Piggin 已提交
1711
	if (write)
H
Hugh Dickins 已提交
1712
		flags |= FOLL_WRITE;
N
Nick Piggin 已提交
1713
	if (force)
H
Hugh Dickins 已提交
1714
		flags |= FOLL_FORCE;
N
Nick Piggin 已提交
1715

1716 1717
	return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
				NULL);
N
Nick Piggin 已提交
1718
}
L
Linus Torvalds 已提交
1719 1720
EXPORT_SYMBOL(get_user_pages);

H
Hugh Dickins 已提交
1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741
/**
 * get_dump_page() - pin user page in memory while writing it to core dump
 * @addr: user address
 *
 * Returns struct page pointer of user page pinned for dump,
 * to be freed afterwards by page_cache_release() or put_page().
 *
 * Returns NULL on any kind of failure - a hole must then be inserted into
 * the corefile, to preserve alignment with its headers; and also returns
 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
 * allowing a hole to be left in the corefile to save diskspace.
 *
 * Called without mmap_sem, but after all other threads have been killed.
 */
#ifdef CONFIG_ELF_CORE
struct page *get_dump_page(unsigned long addr)
{
	struct vm_area_struct *vma;
	struct page *page;

	if (__get_user_pages(current, current->mm, addr, 1,
1742 1743
			     FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
			     NULL) < 1)
H
Hugh Dickins 已提交
1744 1745 1746 1747 1748 1749
		return NULL;
	flush_cache_page(vma, addr, page_to_pfn(page));
	return page;
}
#endif /* CONFIG_ELF_CORE */

1750
pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
H
Harvey Harrison 已提交
1751
			spinlock_t **ptl)
1752 1753 1754 1755
{
	pgd_t * pgd = pgd_offset(mm, addr);
	pud_t * pud = pud_alloc(mm, pgd, addr);
	if (pud) {
1756
		pmd_t * pmd = pmd_alloc(mm, pud, addr);
1757 1758
		if (pmd) {
			VM_BUG_ON(pmd_trans_huge(*pmd));
1759
			return pte_alloc_map_lock(mm, pmd, addr, ptl);
1760
		}
1761 1762 1763 1764
	}
	return NULL;
}

1765 1766 1767 1768 1769 1770 1771
/*
 * This is the old fallback for page remapping.
 *
 * For historical reasons, it only allows reserved pages. Only
 * old drivers should use this, and they needed to mark their
 * pages reserved for the old functions anyway.
 */
N
Nick Piggin 已提交
1772 1773
static int insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page, pgprot_t prot)
1774
{
N
Nick Piggin 已提交
1775
	struct mm_struct *mm = vma->vm_mm;
1776
	int retval;
1777
	pte_t *pte;
1778 1779
	spinlock_t *ptl;

1780
	retval = -EINVAL;
1781
	if (PageAnon(page))
1782
		goto out;
1783 1784
	retval = -ENOMEM;
	flush_dcache_page(page);
1785
	pte = get_locked_pte(mm, addr, &ptl);
1786
	if (!pte)
1787
		goto out;
1788 1789 1790 1791 1792 1793
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	get_page(page);
1794
	inc_mm_counter_fast(mm, MM_FILEPAGES);
1795 1796 1797 1798
	page_add_file_rmap(page);
	set_pte_at(mm, addr, pte, mk_pte(page, prot));

	retval = 0;
1799 1800
	pte_unmap_unlock(pte, ptl);
	return retval;
1801 1802 1803 1804 1805 1806
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

1807 1808 1809 1810 1811 1812
/**
 * vm_insert_page - insert single page into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @page: source kernel page
 *
1813 1814 1815 1816 1817 1818
 * This allows drivers to insert individual pages they've allocated
 * into a user vma.
 *
 * The page has to be a nice clean _individual_ kernel allocation.
 * If you allocate a compound page, you need to have marked it as
 * such (__GFP_COMP), or manually just split the page up yourself
N
Nick Piggin 已提交
1819
 * (see split_page()).
1820 1821 1822 1823 1824 1825 1826 1827 1828
 *
 * NOTE! Traditionally this was done with "remap_pfn_range()" which
 * took an arbitrary page protection parameter. This doesn't allow
 * that. Your vma protection will have to be set up correctly, which
 * means that if you want a shared writable mapping, you'd better
 * ask for a shared writable mapping!
 *
 * The page does not need to be reserved.
 */
N
Nick Piggin 已提交
1829 1830
int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
			struct page *page)
1831 1832 1833 1834 1835
{
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
	if (!page_count(page))
		return -EINVAL;
1836
	vma->vm_flags |= VM_INSERTPAGE;
N
Nick Piggin 已提交
1837
	return insert_page(vma, addr, page, vma->vm_page_prot);
1838
}
1839
EXPORT_SYMBOL(vm_insert_page);
1840

N
Nick Piggin 已提交
1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859
static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn, pgprot_t prot)
{
	struct mm_struct *mm = vma->vm_mm;
	int retval;
	pte_t *pte, entry;
	spinlock_t *ptl;

	retval = -ENOMEM;
	pte = get_locked_pte(mm, addr, &ptl);
	if (!pte)
		goto out;
	retval = -EBUSY;
	if (!pte_none(*pte))
		goto out_unlock;

	/* Ok, finally just insert the thing.. */
	entry = pte_mkspecial(pfn_pte(pfn, prot));
	set_pte_at(mm, addr, pte, entry);
1860
	update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
N
Nick Piggin 已提交
1861 1862 1863 1864 1865 1866 1867 1868

	retval = 0;
out_unlock:
	pte_unmap_unlock(pte, ptl);
out:
	return retval;
}

N
Nick Piggin 已提交
1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879
/**
 * vm_insert_pfn - insert single pfn into user vma
 * @vma: user vma to map to
 * @addr: target user address of this page
 * @pfn: source kernel pfn
 *
 * Similar to vm_inert_page, this allows drivers to insert individual pages
 * they've allocated into a user vma. Same comments apply.
 *
 * This function should only be called from a vm_ops->fault handler, and
 * in that case the handler should return NULL.
N
Nick Piggin 已提交
1880 1881 1882 1883 1884
 *
 * vma cannot be a COW mapping.
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
N
Nick Piggin 已提交
1885 1886
 */
int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
N
Nick Piggin 已提交
1887
			unsigned long pfn)
N
Nick Piggin 已提交
1888
{
1889
	int ret;
1890
	pgprot_t pgprot = vma->vm_page_prot;
N
Nick Piggin 已提交
1891 1892 1893 1894 1895 1896
	/*
	 * Technically, architectures with pte_special can avoid all these
	 * restrictions (same for remap_pfn_range).  However we would like
	 * consistency in testing and feature parity among all, so we should
	 * try to keep these invariants in place for everybody.
	 */
J
Jared Hulbert 已提交
1897 1898 1899 1900 1901
	BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
	BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
						(VM_PFNMAP|VM_MIXEDMAP));
	BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
	BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
N
Nick Piggin 已提交
1902

N
Nick Piggin 已提交
1903 1904
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
1905
	if (track_pfn_vma_new(vma, &pgprot, pfn, PAGE_SIZE))
1906 1907
		return -EINVAL;

1908
	ret = insert_pfn(vma, addr, pfn, pgprot);
1909 1910 1911 1912 1913

	if (ret)
		untrack_pfn_vma(vma, pfn, PAGE_SIZE);

	return ret;
N
Nick Piggin 已提交
1914 1915
}
EXPORT_SYMBOL(vm_insert_pfn);
N
Nick Piggin 已提交
1916

N
Nick Piggin 已提交
1917 1918 1919 1920
int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
			unsigned long pfn)
{
	BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
N
Nick Piggin 已提交
1921

N
Nick Piggin 已提交
1922 1923
	if (addr < vma->vm_start || addr >= vma->vm_end)
		return -EFAULT;
N
Nick Piggin 已提交
1924

N
Nick Piggin 已提交
1925 1926 1927 1928
	/*
	 * If we don't have pte special, then we have to use the pfn_valid()
	 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
	 * refcount the page if pfn_valid is true (hence insert_page rather
H
Hugh Dickins 已提交
1929 1930
	 * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
	 * without pte special, it would there be refcounted as a normal page.
N
Nick Piggin 已提交
1931 1932 1933 1934 1935 1936 1937 1938
	 */
	if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
		struct page *page;

		page = pfn_to_page(pfn);
		return insert_page(vma, addr, page, vma->vm_page_prot);
	}
	return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
N
Nick Piggin 已提交
1939
}
N
Nick Piggin 已提交
1940
EXPORT_SYMBOL(vm_insert_mixed);
N
Nick Piggin 已提交
1941

L
Linus Torvalds 已提交
1942 1943 1944 1945 1946 1947 1948 1949 1950 1951
/*
 * maps a range of physical memory into the requested pages. the old
 * mappings are removed. any references to nonexistent pages results
 * in null mappings (currently treated as "copy-on-access")
 */
static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pte_t *pte;
H
Hugh Dickins 已提交
1952
	spinlock_t *ptl;
L
Linus Torvalds 已提交
1953

H
Hugh Dickins 已提交
1954
	pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
L
Linus Torvalds 已提交
1955 1956
	if (!pte)
		return -ENOMEM;
1957
	arch_enter_lazy_mmu_mode();
L
Linus Torvalds 已提交
1958 1959
	do {
		BUG_ON(!pte_none(*pte));
N
Nick Piggin 已提交
1960
		set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
L
Linus Torvalds 已提交
1961 1962
		pfn++;
	} while (pte++, addr += PAGE_SIZE, addr != end);
1963
	arch_leave_lazy_mmu_mode();
H
Hugh Dickins 已提交
1964
	pte_unmap_unlock(pte - 1, ptl);
L
Linus Torvalds 已提交
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978
	return 0;
}

static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pmd_t *pmd;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
1979
	VM_BUG_ON(pmd_trans_huge(*pmd));
L
Linus Torvalds 已提交
1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
	do {
		next = pmd_addr_end(addr, end);
		if (remap_pte_range(mm, pmd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pmd++, addr = next, addr != end);
	return 0;
}

static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
			unsigned long addr, unsigned long end,
			unsigned long pfn, pgprot_t prot)
{
	pud_t *pud;
	unsigned long next;

	pfn -= addr >> PAGE_SHIFT;
	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		if (remap_pmd_range(mm, pud, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot))
			return -ENOMEM;
	} while (pud++, addr = next, addr != end);
	return 0;
}

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018
/**
 * remap_pfn_range - remap kernel memory to userspace
 * @vma: user vma to map to
 * @addr: target user address to start at
 * @pfn: physical address of kernel memory
 * @size: size of map area
 * @prot: page protection flags for this mapping
 *
 *  Note: this is only safe if the mm semaphore is held when called.
 */
L
Linus Torvalds 已提交
2019 2020 2021 2022 2023
int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
		    unsigned long pfn, unsigned long size, pgprot_t prot)
{
	pgd_t *pgd;
	unsigned long next;
2024
	unsigned long end = addr + PAGE_ALIGN(size);
L
Linus Torvalds 已提交
2025 2026 2027 2028 2029 2030 2031 2032
	struct mm_struct *mm = vma->vm_mm;
	int err;

	/*
	 * Physically remapped pages are special. Tell the
	 * rest of the world about it:
	 *   VM_IO tells people not to look at these pages
	 *	(accesses can have side effects).
H
Hugh Dickins 已提交
2033 2034 2035 2036 2037
	 *   VM_RESERVED is specified all over the place, because
	 *	in 2.4 it kept swapout's vma scan off this vma; but
	 *	in 2.6 the LRU scan won't even find its pages, so this
	 *	flag means no more than count its pages in reserved_vm,
	 * 	and omit it from core dump, even when VM_IO turned off.
2038 2039 2040
	 *   VM_PFNMAP tells the core MM that the base pages are just
	 *	raw PFN mappings, and do not have a "struct page" associated
	 *	with them.
L
Linus Torvalds 已提交
2041 2042 2043 2044
	 *
	 * There's a horrible special case to handle copy-on-write
	 * behaviour that some programs depend on. We mark the "original"
	 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
L
Linus Torvalds 已提交
2045
	 */
2046
	if (addr == vma->vm_start && end == vma->vm_end) {
L
Linus Torvalds 已提交
2047
		vma->vm_pgoff = pfn;
2048
		vma->vm_flags |= VM_PFN_AT_MMAP;
2049
	} else if (is_cow_mapping(vma->vm_flags))
2050
		return -EINVAL;
L
Linus Torvalds 已提交
2051

2052
	vma->vm_flags |= VM_IO | VM_RESERVED | VM_PFNMAP;
L
Linus Torvalds 已提交
2053

2054
	err = track_pfn_vma_new(vma, &prot, pfn, PAGE_ALIGN(size));
2055 2056 2057 2058 2059 2060
	if (err) {
		/*
		 * To indicate that track_pfn related cleanup is not
		 * needed from higher level routine calling unmap_vmas
		 */
		vma->vm_flags &= ~(VM_IO | VM_RESERVED | VM_PFNMAP);
2061
		vma->vm_flags &= ~VM_PFN_AT_MMAP;
2062
		return -EINVAL;
2063
	}
2064

L
Linus Torvalds 已提交
2065 2066 2067 2068 2069 2070 2071 2072 2073 2074 2075
	BUG_ON(addr >= end);
	pfn -= addr >> PAGE_SHIFT;
	pgd = pgd_offset(mm, addr);
	flush_cache_range(vma, addr, end);
	do {
		next = pgd_addr_end(addr, end);
		err = remap_pud_range(mm, pgd, addr, next,
				pfn + (addr >> PAGE_SHIFT), prot);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
2076 2077 2078 2079

	if (err)
		untrack_pfn_vma(vma, pfn, PAGE_ALIGN(size));

L
Linus Torvalds 已提交
2080 2081 2082 2083
	return err;
}
EXPORT_SYMBOL(remap_pfn_range);

2084 2085 2086 2087 2088 2089
static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pte_t *pte;
	int err;
2090
	pgtable_t token;
2091
	spinlock_t *uninitialized_var(ptl);
2092 2093 2094 2095 2096 2097 2098 2099 2100

	pte = (mm == &init_mm) ?
		pte_alloc_kernel(pmd, addr) :
		pte_alloc_map_lock(mm, pmd, addr, &ptl);
	if (!pte)
		return -ENOMEM;

	BUG_ON(pmd_huge(*pmd));

2101 2102
	arch_enter_lazy_mmu_mode();

2103
	token = pmd_pgtable(*pmd);
2104 2105

	do {
2106
		err = fn(pte++, token, addr, data);
2107 2108
		if (err)
			break;
2109
	} while (addr += PAGE_SIZE, addr != end);
2110

2111 2112
	arch_leave_lazy_mmu_mode();

2113 2114 2115 2116 2117 2118 2119 2120 2121 2122 2123 2124 2125
	if (mm != &init_mm)
		pte_unmap_unlock(pte-1, ptl);
	return err;
}

static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pmd_t *pmd;
	unsigned long next;
	int err;

A
Andi Kleen 已提交
2126 2127
	BUG_ON(pud_huge(*pud));

2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156 2157 2158 2159 2160 2161 2162 2163 2164 2165 2166 2167 2168
	pmd = pmd_alloc(mm, pud, addr);
	if (!pmd)
		return -ENOMEM;
	do {
		next = pmd_addr_end(addr, end);
		err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
		if (err)
			break;
	} while (pmd++, addr = next, addr != end);
	return err;
}

static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
				     unsigned long addr, unsigned long end,
				     pte_fn_t fn, void *data)
{
	pud_t *pud;
	unsigned long next;
	int err;

	pud = pud_alloc(mm, pgd, addr);
	if (!pud)
		return -ENOMEM;
	do {
		next = pud_addr_end(addr, end);
		err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
		if (err)
			break;
	} while (pud++, addr = next, addr != end);
	return err;
}

/*
 * Scan a region of virtual memory, filling in page tables as necessary
 * and calling a provided function on each leaf page table.
 */
int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
			unsigned long size, pte_fn_t fn, void *data)
{
	pgd_t *pgd;
	unsigned long next;
2169
	unsigned long end = addr + size;
2170 2171 2172 2173 2174 2175 2176 2177 2178 2179
	int err;

	BUG_ON(addr >= end);
	pgd = pgd_offset(mm, addr);
	do {
		next = pgd_addr_end(addr, end);
		err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
		if (err)
			break;
	} while (pgd++, addr = next, addr != end);
2180

2181 2182 2183 2184
	return err;
}
EXPORT_SYMBOL_GPL(apply_to_page_range);

2185 2186 2187 2188
/*
 * handle_pte_fault chooses page fault handler according to an entry
 * which was read non-atomically.  Before making any commitment, on
 * those architectures or configurations (e.g. i386 with PAE) which
2189
 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2190 2191
 * must check under lock before unmapping the pte and proceeding
 * (but do_wp_page is only called after already making such a check;
2192
 * and do_anonymous_page can safely check later on).
2193
 */
H
Hugh Dickins 已提交
2194
static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2195 2196 2197 2198 2199
				pte_t *page_table, pte_t orig_pte)
{
	int same = 1;
#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
	if (sizeof(pte_t) > sizeof(unsigned long)) {
H
Hugh Dickins 已提交
2200 2201
		spinlock_t *ptl = pte_lockptr(mm, pmd);
		spin_lock(ptl);
2202
		same = pte_same(*page_table, orig_pte);
H
Hugh Dickins 已提交
2203
		spin_unlock(ptl);
2204 2205 2206 2207 2208 2209
	}
#endif
	pte_unmap(page_table);
	return same;
}

2210
static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2211 2212 2213 2214 2215 2216 2217 2218 2219
{
	/*
	 * If the source page was a PFN mapping, we don't have
	 * a "struct page" for it. We do a best-effort copy by
	 * just copying from the original user address. If that
	 * fails, we just zero-fill it. Live with it.
	 */
	if (unlikely(!src)) {
		void *kaddr = kmap_atomic(dst, KM_USER0);
L
Linus Torvalds 已提交
2220 2221 2222 2223 2224 2225 2226 2227 2228
		void __user *uaddr = (void __user *)(va & PAGE_MASK);

		/*
		 * This really shouldn't fail, because the page is there
		 * in the page tables. But it might just be unreadable,
		 * in which case we just give up and fill the result with
		 * zeroes.
		 */
		if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2229
			clear_page(kaddr);
2230
		kunmap_atomic(kaddr, KM_USER0);
2231
		flush_dcache_page(dst);
N
Nick Piggin 已提交
2232 2233
	} else
		copy_user_highpage(dst, src, va, vma);
2234 2235
}

L
Linus Torvalds 已提交
2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249
/*
 * This routine handles present pages, when users try to write
 * to a shared page. It is done by copying the page to a new address
 * and decrementing the shared-page counter for the old page.
 *
 * Note that this routine assumes that the protection checks have been
 * done by the caller (the low-level page fault routine in most cases).
 * Thus we can safely just mark it writable once we've done any necessary
 * COW.
 *
 * We also mark the page dirty at this point even though the page will
 * change only once the write actually happens. This avoids a few races,
 * and potentially makes it more efficient.
 *
2250 2251 2252
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), with pte both mapped and locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2253
 */
2254 2255
static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2256
		spinlock_t *ptl, pte_t orig_pte)
2257
	__releases(ptl)
L
Linus Torvalds 已提交
2258
{
2259
	struct page *old_page, *new_page;
L
Linus Torvalds 已提交
2260
	pte_t entry;
2261
	int ret = 0;
2262
	int page_mkwrite = 0;
2263
	struct page *dirty_page = NULL;
L
Linus Torvalds 已提交
2264

2265
	old_page = vm_normal_page(vma, address, orig_pte);
2266 2267 2268 2269 2270 2271 2272 2273 2274 2275 2276
	if (!old_page) {
		/*
		 * VM_MIXEDMAP !pfn_valid() case
		 *
		 * We should not cow pages in a shared writeable mapping.
		 * Just mark the pages writable as we can't do any dirty
		 * accounting on raw pfn maps.
		 */
		if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
				     (VM_WRITE|VM_SHARED))
			goto reuse;
2277
		goto gotten;
2278
	}
L
Linus Torvalds 已提交
2279

2280
	/*
P
Peter Zijlstra 已提交
2281 2282
	 * Take out anonymous pages first, anonymous shared vmas are
	 * not dirty accountable.
2283
	 */
H
Hugh Dickins 已提交
2284
	if (PageAnon(old_page) && !PageKsm(old_page)) {
2285 2286 2287 2288 2289 2290 2291 2292 2293 2294 2295
		if (!trylock_page(old_page)) {
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);
			lock_page(old_page);
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
				goto unlock;
			}
			page_cache_release(old_page);
P
Peter Zijlstra 已提交
2296
		}
2297
		if (reuse_swap_page(old_page)) {
2298 2299 2300 2301 2302 2303
			/*
			 * The page is all ours.  Move it to our anon_vma so
			 * the rmap code will not search our parent or siblings.
			 * Protected against the rmap code by the page lock.
			 */
			page_move_anon_rmap(old_page, vma, address);
2304 2305 2306
			unlock_page(old_page);
			goto reuse;
		}
2307
		unlock_page(old_page);
P
Peter Zijlstra 已提交
2308
	} else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2309
					(VM_WRITE|VM_SHARED))) {
P
Peter Zijlstra 已提交
2310 2311 2312 2313 2314
		/*
		 * Only catch write-faults on shared writable pages,
		 * read-only shared pages can get COWed by
		 * get_user_pages(.write=1, .force=1).
		 */
2315
		if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2316 2317 2318 2319 2320 2321 2322 2323 2324
			struct vm_fault vmf;
			int tmp;

			vmf.virtual_address = (void __user *)(address &
								PAGE_MASK);
			vmf.pgoff = old_page->index;
			vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
			vmf.page = old_page;

2325 2326 2327 2328 2329 2330 2331 2332 2333 2334 2335
			/*
			 * Notify the address space that the page is about to
			 * become writable so that it can prohibit this or wait
			 * for the page to get into an appropriate state.
			 *
			 * We do this without the lock held, so that it can
			 * sleep if it needs to.
			 */
			page_cache_get(old_page);
			pte_unmap_unlock(page_table, ptl);

2336 2337 2338 2339
			tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
			if (unlikely(tmp &
					(VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
				ret = tmp;
2340
				goto unwritable_page;
2341
			}
N
Nick Piggin 已提交
2342 2343 2344 2345 2346 2347 2348 2349 2350
			if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
				lock_page(old_page);
				if (!old_page->mapping) {
					ret = 0; /* retry the fault */
					unlock_page(old_page);
					goto unwritable_page;
				}
			} else
				VM_BUG_ON(!PageLocked(old_page));
2351 2352 2353 2354 2355 2356 2357 2358 2359

			/*
			 * Since we dropped the lock we need to revalidate
			 * the PTE as someone else may have changed it.  If
			 * they did, we just return, as we can count on the
			 * MMU to tell us if they didn't also make it writable.
			 */
			page_table = pte_offset_map_lock(mm, pmd, address,
							 &ptl);
N
Nick Piggin 已提交
2360 2361
			if (!pte_same(*page_table, orig_pte)) {
				unlock_page(old_page);
2362
				goto unlock;
N
Nick Piggin 已提交
2363
			}
2364 2365

			page_mkwrite = 1;
L
Linus Torvalds 已提交
2366
		}
2367 2368
		dirty_page = old_page;
		get_page(dirty_page);
2369

2370
reuse:
2371 2372 2373
		flush_cache_page(vma, address, pte_pfn(orig_pte));
		entry = pte_mkyoung(orig_pte);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2374
		if (ptep_set_access_flags(vma, address, page_table, entry,1))
2375
			update_mmu_cache(vma, address, page_table);
2376
		pte_unmap_unlock(page_table, ptl);
2377
		ret |= VM_FAULT_WRITE;
2378 2379 2380 2381 2382 2383 2384 2385 2386 2387

		if (!dirty_page)
			return ret;

		/*
		 * Yes, Virginia, this is actually required to prevent a race
		 * with clear_page_dirty_for_io() from clearing the page dirty
		 * bit after it clear all dirty ptes, but before a racing
		 * do_wp_page installs a dirty pte.
		 *
2388
		 * __do_fault is protected similarly.
2389 2390 2391 2392 2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406 2407 2408 2409 2410 2411 2412 2413 2414
		 */
		if (!page_mkwrite) {
			wait_on_page_locked(dirty_page);
			set_page_dirty_balance(dirty_page, page_mkwrite);
		}
		put_page(dirty_page);
		if (page_mkwrite) {
			struct address_space *mapping = dirty_page->mapping;

			set_page_dirty(dirty_page);
			unlock_page(dirty_page);
			page_cache_release(dirty_page);
			if (mapping)	{
				/*
				 * Some device drivers do not set page.mapping
				 * but still dirty their pages
				 */
				balance_dirty_pages_ratelimited(mapping);
			}
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);

		return ret;
L
Linus Torvalds 已提交
2415 2416 2417 2418 2419
	}

	/*
	 * Ok, we need to copy. Oh, well..
	 */
N
Nick Piggin 已提交
2420
	page_cache_get(old_page);
H
Hugh Dickins 已提交
2421
gotten:
2422
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2423 2424

	if (unlikely(anon_vma_prepare(vma)))
2425
		goto oom;
H
Hugh Dickins 已提交
2426

H
Hugh Dickins 已提交
2427
	if (is_zero_pfn(pte_pfn(orig_pte))) {
H
Hugh Dickins 已提交
2428 2429 2430 2431 2432 2433 2434 2435 2436 2437 2438
		new_page = alloc_zeroed_user_highpage_movable(vma, address);
		if (!new_page)
			goto oom;
	} else {
		new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
		if (!new_page)
			goto oom;
		cow_user_page(new_page, old_page, address, vma);
	}
	__SetPageUptodate(new_page);

K
KAMEZAWA Hiroyuki 已提交
2439
	if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL))
2440 2441
		goto oom_free_new;

L
Linus Torvalds 已提交
2442 2443 2444
	/*
	 * Re-check the pte - we dropped the lock
	 */
2445
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2446
	if (likely(pte_same(*page_table, orig_pte))) {
H
Hugh Dickins 已提交
2447 2448
		if (old_page) {
			if (!PageAnon(old_page)) {
2449 2450
				dec_mm_counter_fast(mm, MM_FILEPAGES);
				inc_mm_counter_fast(mm, MM_ANONPAGES);
H
Hugh Dickins 已提交
2451 2452
			}
		} else
2453
			inc_mm_counter_fast(mm, MM_ANONPAGES);
2454
		flush_cache_page(vma, address, pte_pfn(orig_pte));
2455 2456
		entry = mk_pte(new_page, vma->vm_page_prot);
		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2457 2458 2459 2460 2461 2462
		/*
		 * Clear the pte entry and flush it first, before updating the
		 * pte with the new entry. This will avoid a race condition
		 * seen in the presence of one thread doing SMC and another
		 * thread doing COW.
		 */
2463
		ptep_clear_flush(vma, address, page_table);
N
Nick Piggin 已提交
2464
		page_add_new_anon_rmap(new_page, vma, address);
2465 2466 2467 2468 2469 2470
		/*
		 * We call the notify macro here because, when using secondary
		 * mmu page tables (such as kvm shadow page tables), we want the
		 * new page to be mapped directly into the secondary page table.
		 */
		set_pte_at_notify(mm, address, page_table, entry);
2471
		update_mmu_cache(vma, address, page_table);
N
Nick Piggin 已提交
2472 2473 2474 2475 2476 2477 2478 2479 2480 2481 2482 2483 2484 2485 2486 2487 2488 2489 2490 2491 2492 2493 2494
		if (old_page) {
			/*
			 * Only after switching the pte to the new page may
			 * we remove the mapcount here. Otherwise another
			 * process may come and find the rmap count decremented
			 * before the pte is switched to the new page, and
			 * "reuse" the old page writing into it while our pte
			 * here still points into it and can be read by other
			 * threads.
			 *
			 * The critical issue is to order this
			 * page_remove_rmap with the ptp_clear_flush above.
			 * Those stores are ordered by (if nothing else,)
			 * the barrier present in the atomic_add_negative
			 * in page_remove_rmap.
			 *
			 * Then the TLB flush in ptep_clear_flush ensures that
			 * no process can access the old page before the
			 * decremented mapcount is visible. And the old page
			 * cannot be reused until after the decremented
			 * mapcount is visible. So transitively, TLBs to
			 * old page will be flushed before it can be reused.
			 */
2495
			page_remove_rmap(old_page);
N
Nick Piggin 已提交
2496 2497
		}

L
Linus Torvalds 已提交
2498 2499
		/* Free the old page.. */
		new_page = old_page;
N
Nick Piggin 已提交
2500
		ret |= VM_FAULT_WRITE;
2501 2502 2503
	} else
		mem_cgroup_uncharge_page(new_page);

H
Hugh Dickins 已提交
2504 2505
	if (new_page)
		page_cache_release(new_page);
2506
unlock:
2507
	pte_unmap_unlock(page_table, ptl);
2508 2509 2510 2511 2512 2513 2514 2515 2516 2517 2518 2519
	if (old_page) {
		/*
		 * Don't let another task, with possibly unlocked vma,
		 * keep the mlocked page.
		 */
		if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
			lock_page(old_page);	/* LRU manipulation */
			munlock_vma_page(old_page);
			unlock_page(old_page);
		}
		page_cache_release(old_page);
	}
N
Nick Piggin 已提交
2520
	return ret;
2521
oom_free_new:
2522
	page_cache_release(new_page);
2523
oom:
N
Nick Piggin 已提交
2524 2525 2526 2527 2528
	if (old_page) {
		if (page_mkwrite) {
			unlock_page(old_page);
			page_cache_release(old_page);
		}
H
Hugh Dickins 已提交
2529
		page_cache_release(old_page);
N
Nick Piggin 已提交
2530
	}
L
Linus Torvalds 已提交
2531
	return VM_FAULT_OOM;
2532 2533 2534

unwritable_page:
	page_cache_release(old_page);
2535
	return ret;
L
Linus Torvalds 已提交
2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562
}

/*
 * Helper functions for unmap_mapping_range().
 *
 * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
 *
 * We have to restart searching the prio_tree whenever we drop the lock,
 * since the iterator is only valid while the lock is held, and anyway
 * a later vma might be split and reinserted earlier while lock dropped.
 *
 * The list of nonlinear vmas could be handled more efficiently, using
 * a placeholder, but handle it in the same way until a need is shown.
 * It is important to search the prio_tree before nonlinear list: a vma
 * may become nonlinear and be shifted from prio_tree to nonlinear list
 * while the lock is dropped; but never shifted from list to prio_tree.
 *
 * In order to make forward progress despite restarting the search,
 * vm_truncate_count is used to mark a vma as now dealt with, so we can
 * quickly skip it next time around.  Since the prio_tree search only
 * shows us those vmas affected by unmapping the range in question, we
 * can't efficiently keep all vmas in step with mapping->truncate_count:
 * so instead reset them all whenever it wraps back to 0 (then go to 1).
 * mapping->truncate_count and vma->vm_truncate_count are protected by
 * i_mmap_lock.
 *
 * In order to make forward progress despite repeatedly restarting some
2563
 * large vma, note the restart_addr from unmap_vmas when it breaks out:
L
Linus Torvalds 已提交
2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589
 * and restart from that address when we reach that vma again.  It might
 * have been split or merged, shrunk or extended, but never shifted: so
 * restart_addr remains valid so long as it remains in the vma's range.
 * unmap_mapping_range forces truncate_count to leap over page-aligned
 * values so we can save vma's restart_addr in its truncate_count field.
 */
#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))

static void reset_vma_truncate_counts(struct address_space *mapping)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;

	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
		vma->vm_truncate_count = 0;
	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
		vma->vm_truncate_count = 0;
}

static int unmap_mapping_range_vma(struct vm_area_struct *vma,
		unsigned long start_addr, unsigned long end_addr,
		struct zap_details *details)
{
	unsigned long restart_addr;
	int need_break;

2590 2591
	/*
	 * files that support invalidating or truncating portions of the
N
Nick Piggin 已提交
2592
	 * file from under mmaped areas must have their ->fault function
N
Nick Piggin 已提交
2593 2594
	 * return a locked page (and set VM_FAULT_LOCKED in the return).
	 * This provides synchronisation against concurrent unmapping here.
2595 2596
	 */

L
Linus Torvalds 已提交
2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607
again:
	restart_addr = vma->vm_truncate_count;
	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
		start_addr = restart_addr;
		if (start_addr >= end_addr) {
			/* Top of vma has been split off since last time */
			vma->vm_truncate_count = details->truncate_count;
			return 0;
		}
	}

2608 2609
	restart_addr = zap_page_range(vma, start_addr,
					end_addr - start_addr, details);
N
Nick Piggin 已提交
2610
	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
L
Linus Torvalds 已提交
2611

2612
	if (restart_addr >= end_addr) {
L
Linus Torvalds 已提交
2613 2614 2615 2616 2617 2618
		/* We have now completed this vma: mark it so */
		vma->vm_truncate_count = details->truncate_count;
		if (!need_break)
			return 0;
	} else {
		/* Note restart_addr in vma's truncate_count field */
2619
		vma->vm_truncate_count = restart_addr;
L
Linus Torvalds 已提交
2620 2621 2622 2623 2624 2625 2626 2627 2628 2629 2630 2631 2632 2633 2634 2635 2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666 2667 2668 2669 2670 2671 2672 2673 2674 2675 2676 2677 2678 2679 2680 2681 2682 2683 2684 2685
		if (!need_break)
			goto again;
	}

	spin_unlock(details->i_mmap_lock);
	cond_resched();
	spin_lock(details->i_mmap_lock);
	return -EINTR;
}

static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;
	struct prio_tree_iter iter;
	pgoff_t vba, vea, zba, zea;

restart:
	vma_prio_tree_foreach(vma, &iter, root,
			details->first_index, details->last_index) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;

		vba = vma->vm_pgoff;
		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
		/* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
		zba = details->first_index;
		if (zba < vba)
			zba = vba;
		zea = details->last_index;
		if (zea > vea)
			zea = vea;

		if (unmap_mapping_range_vma(vma,
			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
				details) < 0)
			goto restart;
	}
}

static inline void unmap_mapping_range_list(struct list_head *head,
					    struct zap_details *details)
{
	struct vm_area_struct *vma;

	/*
	 * In nonlinear VMAs there is no correspondence between virtual address
	 * offset and file offset.  So we must perform an exhaustive search
	 * across *all* the pages in each nonlinear VMA, not just the pages
	 * whose virtual address lies outside the file truncation point.
	 */
restart:
	list_for_each_entry(vma, head, shared.vm_set.list) {
		/* Skip quickly over those we have already dealt with */
		if (vma->vm_truncate_count == details->truncate_count)
			continue;
		details->nonlinear_vma = vma;
		if (unmap_mapping_range_vma(vma, vma->vm_start,
					vma->vm_end, details) < 0)
			goto restart;
	}
}

/**
2686
 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
M
Martin Waitz 已提交
2687
 * @mapping: the address space containing mmaps to be unmapped.
L
Linus Torvalds 已提交
2688 2689
 * @holebegin: byte in first page to unmap, relative to the start of
 * the underlying file.  This will be rounded down to a PAGE_SIZE
N
npiggin@suse.de 已提交
2690
 * boundary.  Note that this is different from truncate_pagecache(), which
L
Linus Torvalds 已提交
2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705 2706 2707 2708 2709 2710 2711 2712 2713 2714 2715 2716 2717 2718 2719 2720 2721
 * must keep the partial page.  In contrast, we must get rid of
 * partial pages.
 * @holelen: size of prospective hole in bytes.  This will be rounded
 * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
 * end of the file.
 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
 * but 0 when invalidating pagecache, don't throw away private data.
 */
void unmap_mapping_range(struct address_space *mapping,
		loff_t const holebegin, loff_t const holelen, int even_cows)
{
	struct zap_details details;
	pgoff_t hba = holebegin >> PAGE_SHIFT;
	pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;

	/* Check for overflow. */
	if (sizeof(holelen) > sizeof(hlen)) {
		long long holeend =
			(holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
		if (holeend & ~(long long)ULONG_MAX)
			hlen = ULONG_MAX - hba + 1;
	}

	details.check_mapping = even_cows? NULL: mapping;
	details.nonlinear_vma = NULL;
	details.first_index = hba;
	details.last_index = hba + hlen - 1;
	if (details.last_index < details.first_index)
		details.last_index = ULONG_MAX;
	details.i_mmap_lock = &mapping->i_mmap_lock;

2722
	mutex_lock(&mapping->unmap_mutex);
L
Linus Torvalds 已提交
2723 2724
	spin_lock(&mapping->i_mmap_lock);

2725
	/* Protect against endless unmapping loops */
L
Linus Torvalds 已提交
2726 2727 2728 2729 2730 2731 2732 2733 2734 2735 2736 2737 2738
	mapping->truncate_count++;
	if (unlikely(is_restart_addr(mapping->truncate_count))) {
		if (mapping->truncate_count == 0)
			reset_vma_truncate_counts(mapping);
		mapping->truncate_count++;
	}
	details.truncate_count = mapping->truncate_count;

	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
		unmap_mapping_range_tree(&mapping->i_mmap, &details);
	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
	spin_unlock(&mapping->i_mmap_lock);
2739
	mutex_unlock(&mapping->unmap_mutex);
L
Linus Torvalds 已提交
2740 2741 2742
}
EXPORT_SYMBOL(unmap_mapping_range);

2743 2744 2745 2746 2747 2748 2749 2750 2751
int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
{
	struct address_space *mapping = inode->i_mapping;

	/*
	 * If the underlying filesystem is not going to provide
	 * a way to truncate a range of blocks (punch a hole) -
	 * we should return failure right now.
	 */
A
Al Viro 已提交
2752
	if (!inode->i_op->truncate_range)
2753 2754
		return -ENOSYS;

2755
	mutex_lock(&inode->i_mutex);
2756 2757 2758
	down_write(&inode->i_alloc_sem);
	unmap_mapping_range(mapping, offset, (end - offset), 1);
	truncate_inode_pages_range(mapping, offset, end);
2759
	unmap_mapping_range(mapping, offset, (end - offset), 1);
2760 2761
	inode->i_op->truncate_range(inode, offset, end);
	up_write(&inode->i_alloc_sem);
2762
	mutex_unlock(&inode->i_mutex);
2763 2764 2765 2766

	return 0;
}

L
Linus Torvalds 已提交
2767
/*
2768 2769 2770
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2771
 */
2772 2773
static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2774
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
2775
{
2776
	spinlock_t *ptl;
A
Andrea Arcangeli 已提交
2777
	struct page *page, *swapcache = NULL;
2778
	swp_entry_t entry;
L
Linus Torvalds 已提交
2779
	pte_t pte;
2780
	int locked;
2781
	struct mem_cgroup *ptr;
2782
	int exclusive = 0;
N
Nick Piggin 已提交
2783
	int ret = 0;
L
Linus Torvalds 已提交
2784

H
Hugh Dickins 已提交
2785
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
2786
		goto out;
2787 2788

	entry = pte_to_swp_entry(orig_pte);
2789 2790 2791 2792 2793 2794 2795
	if (unlikely(non_swap_entry(entry))) {
		if (is_migration_entry(entry)) {
			migration_entry_wait(mm, pmd, address);
		} else if (is_hwpoison_entry(entry)) {
			ret = VM_FAULT_HWPOISON;
		} else {
			print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
2796
			ret = VM_FAULT_SIGBUS;
2797
		}
2798 2799
		goto out;
	}
2800
	delayacct_set_flag(DELAYACCT_PF_SWAPIN);
L
Linus Torvalds 已提交
2801 2802
	page = lookup_swap_cache(entry);
	if (!page) {
H
Hugh Dickins 已提交
2803
		grab_swap_token(mm); /* Contend for token _before_ read-in */
2804 2805
		page = swapin_readahead(entry,
					GFP_HIGHUSER_MOVABLE, vma, address);
L
Linus Torvalds 已提交
2806 2807
		if (!page) {
			/*
2808 2809
			 * Back out if somebody else faulted in this pte
			 * while we released the pte lock.
L
Linus Torvalds 已提交
2810
			 */
2811
			page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
2812 2813
			if (likely(pte_same(*page_table, orig_pte)))
				ret = VM_FAULT_OOM;
2814
			delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2815
			goto unlock;
L
Linus Torvalds 已提交
2816 2817 2818 2819
		}

		/* Had to read the page from swap area: Major fault */
		ret = VM_FAULT_MAJOR;
2820
		count_vm_event(PGMAJFAULT);
2821
	} else if (PageHWPoison(page)) {
2822 2823 2824 2825
		/*
		 * hwpoisoned dirty swapcache pages are kept for killing
		 * owner processes (which may be unknown at hwpoison time)
		 */
2826 2827
		ret = VM_FAULT_HWPOISON;
		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2828
		goto out_release;
L
Linus Torvalds 已提交
2829 2830
	}

2831
	locked = lock_page_or_retry(page, mm, flags);
2832
	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2833 2834 2835 2836
	if (!locked) {
		ret |= VM_FAULT_RETRY;
		goto out_release;
	}
2837

A
Andrea Arcangeli 已提交
2838
	/*
2839 2840 2841 2842
	 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
	 * release the swapcache from under us.  The page pin, and pte_same
	 * test below, are not enough to exclude that.  Even if it is still
	 * swapcache, we need to check that the page's swap has not changed.
A
Andrea Arcangeli 已提交
2843
	 */
2844
	if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
A
Andrea Arcangeli 已提交
2845 2846 2847 2848 2849 2850 2851 2852 2853 2854 2855 2856
		goto out_page;

	if (ksm_might_need_to_copy(page, vma, address)) {
		swapcache = page;
		page = ksm_does_need_to_copy(page, vma, address);

		if (unlikely(!page)) {
			ret = VM_FAULT_OOM;
			page = swapcache;
			swapcache = NULL;
			goto out_page;
		}
H
Hugh Dickins 已提交
2857 2858
	}

K
KAMEZAWA Hiroyuki 已提交
2859
	if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
2860
		ret = VM_FAULT_OOM;
2861
		goto out_page;
2862 2863
	}

L
Linus Torvalds 已提交
2864
	/*
2865
	 * Back out if somebody else already faulted in this pte.
L
Linus Torvalds 已提交
2866
	 */
2867
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
2868
	if (unlikely(!pte_same(*page_table, orig_pte)))
2869 2870 2871 2872 2873
		goto out_nomap;

	if (unlikely(!PageUptodate(page))) {
		ret = VM_FAULT_SIGBUS;
		goto out_nomap;
L
Linus Torvalds 已提交
2874 2875
	}

2876 2877 2878 2879 2880 2881 2882 2883
	/*
	 * The page isn't present yet, go ahead with the fault.
	 *
	 * Be careful about the sequence of operations here.
	 * To get its accounting right, reuse_swap_page() must be called
	 * while the page is counted on swap but not yet in mapcount i.e.
	 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
	 * must be called after the swap_free(), or it will never succeed.
2884 2885 2886 2887
	 * Because delete_from_swap_page() may be called by reuse_swap_page(),
	 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
	 * in page->private. In this case, a record in swap_cgroup  is silently
	 * discarded at swap_free().
2888
	 */
L
Linus Torvalds 已提交
2889

2890
	inc_mm_counter_fast(mm, MM_ANONPAGES);
K
KAMEZAWA Hiroyuki 已提交
2891
	dec_mm_counter_fast(mm, MM_SWAPENTS);
L
Linus Torvalds 已提交
2892
	pte = mk_pte(page, vma->vm_page_prot);
2893
	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
L
Linus Torvalds 已提交
2894
		pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2895
		flags &= ~FAULT_FLAG_WRITE;
2896
		ret |= VM_FAULT_WRITE;
2897
		exclusive = 1;
L
Linus Torvalds 已提交
2898 2899 2900
	}
	flush_icache_page(vma, page);
	set_pte_at(mm, address, page_table, pte);
2901
	do_page_add_anon_rmap(page, vma, address, exclusive);
2902 2903
	/* It's better to call commit-charge after rmap is established */
	mem_cgroup_commit_charge_swapin(page, ptr);
L
Linus Torvalds 已提交
2904

2905
	swap_free(entry);
N
Nick Piggin 已提交
2906
	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2907
		try_to_free_swap(page);
2908
	unlock_page(page);
A
Andrea Arcangeli 已提交
2909 2910 2911 2912 2913 2914 2915 2916 2917 2918 2919 2920
	if (swapcache) {
		/*
		 * Hold the lock to avoid the swap entry to be reused
		 * until we take the PT lock for the pte_same() check
		 * (to avoid false positives from pte_same). For
		 * further safety release the lock after the swap_free
		 * so that the swap count won't change under a
		 * parallel locked swapcache.
		 */
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2921

2922
	if (flags & FAULT_FLAG_WRITE) {
2923 2924 2925
		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
		if (ret & VM_FAULT_ERROR)
			ret &= VM_FAULT_ERROR;
L
Linus Torvalds 已提交
2926 2927 2928 2929
		goto out;
	}

	/* No need to invalidate - it was non-present before */
2930
	update_mmu_cache(vma, address, page_table);
2931
unlock:
2932
	pte_unmap_unlock(page_table, ptl);
L
Linus Torvalds 已提交
2933 2934
out:
	return ret;
2935
out_nomap:
2936
	mem_cgroup_cancel_charge_swapin(ptr);
2937
	pte_unmap_unlock(page_table, ptl);
2938
out_page:
2939
	unlock_page(page);
2940
out_release:
2941
	page_cache_release(page);
A
Andrea Arcangeli 已提交
2942 2943 2944 2945
	if (swapcache) {
		unlock_page(swapcache);
		page_cache_release(swapcache);
	}
2946
	return ret;
L
Linus Torvalds 已提交
2947 2948
}

2949
/*
2950 2951
 * This is like a special single-page "expand_{down|up}wards()",
 * except we must first make sure that 'address{-|+}PAGE_SIZE'
2952 2953 2954 2955 2956 2957
 * doesn't hit another vma.
 */
static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
{
	address &= PAGE_MASK;
	if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
2958 2959 2960 2961 2962 2963 2964 2965 2966 2967
		struct vm_area_struct *prev = vma->vm_prev;

		/*
		 * Is there a mapping abutting this one below?
		 *
		 * That's only ok if it's the same stack mapping
		 * that has gotten split..
		 */
		if (prev && prev->vm_end == address)
			return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
2968

2969
		expand_downwards(vma, address - PAGE_SIZE);
2970
	}
2971 2972 2973 2974 2975 2976 2977 2978 2979
	if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
		struct vm_area_struct *next = vma->vm_next;

		/* As VM_GROWSDOWN but s/below/above/ */
		if (next && next->vm_start == address + PAGE_SIZE)
			return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;

		expand_upwards(vma, address + PAGE_SIZE);
	}
2980 2981 2982
	return 0;
}

L
Linus Torvalds 已提交
2983
/*
2984 2985 2986
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
2987
 */
2988 2989
static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
2990
		unsigned int flags)
L
Linus Torvalds 已提交
2991
{
2992 2993
	struct page *page;
	spinlock_t *ptl;
L
Linus Torvalds 已提交
2994 2995
	pte_t entry;

2996 2997 2998 2999
	pte_unmap(page_table);

	/* Check if we need to add a guard page to the stack */
	if (check_stack_guard_page(vma, address) < 0)
3000 3001
		return VM_FAULT_SIGBUS;

3002
	/* Use the zero-page for reads */
H
Hugh Dickins 已提交
3003 3004 3005
	if (!(flags & FAULT_FLAG_WRITE)) {
		entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
						vma->vm_page_prot));
3006
		page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
H
Hugh Dickins 已提交
3007 3008 3009 3010 3011
		if (!pte_none(*page_table))
			goto unlock;
		goto setpte;
	}

N
Nick Piggin 已提交
3012 3013 3014 3015 3016 3017
	/* Allocate our own private page. */
	if (unlikely(anon_vma_prepare(vma)))
		goto oom;
	page = alloc_zeroed_user_highpage_movable(vma, address);
	if (!page)
		goto oom;
N
Nick Piggin 已提交
3018
	__SetPageUptodate(page);
3019

K
KAMEZAWA Hiroyuki 已提交
3020
	if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL))
3021 3022
		goto oom_free_page;

N
Nick Piggin 已提交
3023
	entry = mk_pte(page, vma->vm_page_prot);
H
Hugh Dickins 已提交
3024 3025
	if (vma->vm_flags & VM_WRITE)
		entry = pte_mkwrite(pte_mkdirty(entry));
L
Linus Torvalds 已提交
3026

N
Nick Piggin 已提交
3027
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3028
	if (!pte_none(*page_table))
N
Nick Piggin 已提交
3029
		goto release;
H
Hugh Dickins 已提交
3030

3031
	inc_mm_counter_fast(mm, MM_ANONPAGES);
N
Nick Piggin 已提交
3032
	page_add_new_anon_rmap(page, vma, address);
H
Hugh Dickins 已提交
3033
setpte:
3034
	set_pte_at(mm, address, page_table, entry);
L
Linus Torvalds 已提交
3035 3036

	/* No need to invalidate - it was non-present before */
3037
	update_mmu_cache(vma, address, page_table);
3038
unlock:
3039
	pte_unmap_unlock(page_table, ptl);
N
Nick Piggin 已提交
3040
	return 0;
3041
release:
3042
	mem_cgroup_uncharge_page(page);
3043 3044
	page_cache_release(page);
	goto unlock;
3045
oom_free_page:
3046
	page_cache_release(page);
3047
oom:
L
Linus Torvalds 已提交
3048 3049 3050 3051
	return VM_FAULT_OOM;
}

/*
3052
 * __do_fault() tries to create a new page mapping. It aggressively
L
Linus Torvalds 已提交
3053
 * tries to share with existing pages, but makes a separate copy if
3054 3055
 * the FAULT_FLAG_WRITE is set in the flags parameter in order to avoid
 * the next page fault.
L
Linus Torvalds 已提交
3056 3057 3058 3059
 *
 * As this is called only for pages that do not currently exist, we
 * do not need to flush old virtual caches or the TLB.
 *
3060
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3061
 * but allow concurrent faults), and pte neither mapped nor locked.
3062
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3063
 */
3064
static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3065
		unsigned long address, pmd_t *pmd,
3066
		pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3067
{
3068
	pte_t *page_table;
3069
	spinlock_t *ptl;
N
Nick Piggin 已提交
3070
	struct page *page;
L
Linus Torvalds 已提交
3071 3072
	pte_t entry;
	int anon = 0;
3073
	int charged = 0;
3074
	struct page *dirty_page = NULL;
N
Nick Piggin 已提交
3075 3076
	struct vm_fault vmf;
	int ret;
3077
	int page_mkwrite = 0;
3078

N
Nick Piggin 已提交
3079 3080 3081 3082
	vmf.virtual_address = (void __user *)(address & PAGE_MASK);
	vmf.pgoff = pgoff;
	vmf.flags = flags;
	vmf.page = NULL;
L
Linus Torvalds 已提交
3083

N
Nick Piggin 已提交
3084
	ret = vma->vm_ops->fault(vma, &vmf);
3085 3086
	if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
			    VM_FAULT_RETRY)))
N
Nick Piggin 已提交
3087
		return ret;
L
Linus Torvalds 已提交
3088

3089 3090 3091 3092 3093 3094
	if (unlikely(PageHWPoison(vmf.page))) {
		if (ret & VM_FAULT_LOCKED)
			unlock_page(vmf.page);
		return VM_FAULT_HWPOISON;
	}

3095
	/*
N
Nick Piggin 已提交
3096
	 * For consistency in subsequent calls, make the faulted page always
3097 3098
	 * locked.
	 */
N
Nick Piggin 已提交
3099
	if (unlikely(!(ret & VM_FAULT_LOCKED)))
N
Nick Piggin 已提交
3100
		lock_page(vmf.page);
3101
	else
N
Nick Piggin 已提交
3102
		VM_BUG_ON(!PageLocked(vmf.page));
3103

L
Linus Torvalds 已提交
3104 3105 3106
	/*
	 * Should we do an early C-O-W break?
	 */
N
Nick Piggin 已提交
3107
	page = vmf.page;
3108
	if (flags & FAULT_FLAG_WRITE) {
3109
		if (!(vma->vm_flags & VM_SHARED)) {
3110
			anon = 1;
3111
			if (unlikely(anon_vma_prepare(vma))) {
N
Nick Piggin 已提交
3112
				ret = VM_FAULT_OOM;
3113
				goto out;
3114
			}
N
Nick Piggin 已提交
3115 3116
			page = alloc_page_vma(GFP_HIGHUSER_MOVABLE,
						vma, address);
3117
			if (!page) {
N
Nick Piggin 已提交
3118
				ret = VM_FAULT_OOM;
3119
				goto out;
3120
			}
K
KAMEZAWA Hiroyuki 已提交
3121
			if (mem_cgroup_newpage_charge(page, mm, GFP_KERNEL)) {
3122 3123 3124 3125 3126
				ret = VM_FAULT_OOM;
				page_cache_release(page);
				goto out;
			}
			charged = 1;
N
Nick Piggin 已提交
3127
			copy_user_highpage(page, vmf.page, address, vma);
N
Nick Piggin 已提交
3128
			__SetPageUptodate(page);
3129
		} else {
3130 3131
			/*
			 * If the page will be shareable, see if the backing
3132
			 * address space wants to know that the page is about
3133 3134
			 * to become writable
			 */
3135
			if (vma->vm_ops->page_mkwrite) {
3136 3137
				int tmp;

3138
				unlock_page(page);
N
Nick Piggin 已提交
3139
				vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3140 3141 3142 3143
				tmp = vma->vm_ops->page_mkwrite(vma, &vmf);
				if (unlikely(tmp &
					  (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
					ret = tmp;
N
Nick Piggin 已提交
3144
					goto unwritable_page;
N
Nick Piggin 已提交
3145
				}
N
Nick Piggin 已提交
3146 3147 3148 3149 3150 3151 3152 3153 3154
				if (unlikely(!(tmp & VM_FAULT_LOCKED))) {
					lock_page(page);
					if (!page->mapping) {
						ret = 0; /* retry the fault */
						unlock_page(page);
						goto unwritable_page;
					}
				} else
					VM_BUG_ON(!PageLocked(page));
3155
				page_mkwrite = 1;
3156 3157
			}
		}
3158

L
Linus Torvalds 已提交
3159 3160
	}

3161
	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
L
Linus Torvalds 已提交
3162 3163 3164 3165 3166 3167

	/*
	 * This silly early PAGE_DIRTY setting removes a race
	 * due to the bad i386 page protection. But it's valid
	 * for other architectures too.
	 *
3168
	 * Note that if FAULT_FLAG_WRITE is set, we either now have
L
Linus Torvalds 已提交
3169 3170 3171 3172 3173
	 * an exclusive copy of the page, or this is a shared mapping,
	 * so we can make it writable and dirty to avoid having to
	 * handle that later.
	 */
	/* Only go through if we didn't race with anybody else... */
3174
	if (likely(pte_same(*page_table, orig_pte))) {
3175 3176
		flush_icache_page(vma, page);
		entry = mk_pte(page, vma->vm_page_prot);
3177
		if (flags & FAULT_FLAG_WRITE)
L
Linus Torvalds 已提交
3178 3179
			entry = maybe_mkwrite(pte_mkdirty(entry), vma);
		if (anon) {
3180
			inc_mm_counter_fast(mm, MM_ANONPAGES);
3181
			page_add_new_anon_rmap(page, vma, address);
3182
		} else {
3183
			inc_mm_counter_fast(mm, MM_FILEPAGES);
3184
			page_add_file_rmap(page);
3185
			if (flags & FAULT_FLAG_WRITE) {
3186
				dirty_page = page;
3187 3188
				get_page(dirty_page);
			}
3189
		}
3190
		set_pte_at(mm, address, page_table, entry);
3191 3192

		/* no need to invalidate: a not-present page won't be cached */
3193
		update_mmu_cache(vma, address, page_table);
L
Linus Torvalds 已提交
3194
	} else {
3195 3196
		if (charged)
			mem_cgroup_uncharge_page(page);
3197 3198 3199
		if (anon)
			page_cache_release(page);
		else
3200
			anon = 1; /* no anon but release faulted_page */
L
Linus Torvalds 已提交
3201 3202
	}

3203
	pte_unmap_unlock(page_table, ptl);
3204 3205

out:
N
Nick Piggin 已提交
3206 3207
	if (dirty_page) {
		struct address_space *mapping = page->mapping;
3208

N
Nick Piggin 已提交
3209 3210 3211
		if (set_page_dirty(dirty_page))
			page_mkwrite = 1;
		unlock_page(dirty_page);
3212
		put_page(dirty_page);
N
Nick Piggin 已提交
3213 3214 3215 3216 3217 3218 3219 3220 3221 3222 3223 3224 3225 3226 3227
		if (page_mkwrite && mapping) {
			/*
			 * Some device drivers do not set page.mapping but still
			 * dirty their pages
			 */
			balance_dirty_pages_ratelimited(mapping);
		}

		/* file_update_time outside page_lock */
		if (vma->vm_file)
			file_update_time(vma->vm_file);
	} else {
		unlock_page(vmf.page);
		if (anon)
			page_cache_release(vmf.page);
3228
	}
3229

N
Nick Piggin 已提交
3230
	return ret;
N
Nick Piggin 已提交
3231 3232 3233 3234

unwritable_page:
	page_cache_release(page);
	return ret;
3235
}
3236

3237 3238
static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3239
		unsigned int flags, pte_t orig_pte)
3240 3241
{
	pgoff_t pgoff = (((address & PAGE_MASK)
3242
			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3243

3244 3245
	pte_unmap(page_table);
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3246 3247
}

L
Linus Torvalds 已提交
3248 3249 3250 3251
/*
 * Fault of a previously existing named mapping. Repopulate the pte
 * from the encoded file_pte if possible. This enables swappable
 * nonlinear vmas.
3252 3253 3254 3255
 *
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3256
 */
N
Nick Piggin 已提交
3257
static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3258
		unsigned long address, pte_t *page_table, pmd_t *pmd,
3259
		unsigned int flags, pte_t orig_pte)
L
Linus Torvalds 已提交
3260
{
3261
	pgoff_t pgoff;
L
Linus Torvalds 已提交
3262

3263 3264
	flags |= FAULT_FLAG_NONLINEAR;

H
Hugh Dickins 已提交
3265
	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
N
Nick Piggin 已提交
3266
		return 0;
L
Linus Torvalds 已提交
3267

3268
	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3269 3270 3271
		/*
		 * Page table corrupted: show pte and kill process.
		 */
3272
		print_bad_pte(vma, address, orig_pte, NULL);
H
Hugh Dickins 已提交
3273
		return VM_FAULT_SIGBUS;
3274 3275 3276
	}

	pgoff = pte_to_pgoff(orig_pte);
3277
	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
L
Linus Torvalds 已提交
3278 3279 3280 3281 3282 3283 3284 3285 3286 3287 3288
}

/*
 * These routines also need to handle stuff like marking pages dirty
 * and/or accessed for architectures that don't do it in hardware (most
 * RISC architectures).  The early dirtying is also good on the i386.
 *
 * There is also a hook called "update_mmu_cache()" that architectures
 * with external mmu caches can use to update those (ie the Sparc or
 * PowerPC hashed page tables that act as extended TLBs).
 *
H
Hugh Dickins 已提交
3289 3290 3291
 * We enter with non-exclusive mmap_sem (to exclude vma changes,
 * but allow concurrent faults), and pte mapped but not yet locked.
 * We return with mmap_sem still held, but pte unmapped and unlocked.
L
Linus Torvalds 已提交
3292
 */
3293 3294 3295
int handle_pte_fault(struct mm_struct *mm,
		     struct vm_area_struct *vma, unsigned long address,
		     pte_t *pte, pmd_t *pmd, unsigned int flags)
L
Linus Torvalds 已提交
3296 3297
{
	pte_t entry;
3298
	spinlock_t *ptl;
L
Linus Torvalds 已提交
3299

3300
	entry = *pte;
L
Linus Torvalds 已提交
3301
	if (!pte_present(entry)) {
3302
		if (pte_none(entry)) {
J
Jes Sorensen 已提交
3303
			if (vma->vm_ops) {
N
Nick Piggin 已提交
3304
				if (likely(vma->vm_ops->fault))
3305
					return do_linear_fault(mm, vma, address,
3306
						pte, pmd, flags, entry);
J
Jes Sorensen 已提交
3307 3308
			}
			return do_anonymous_page(mm, vma, address,
3309
						 pte, pmd, flags);
3310
		}
L
Linus Torvalds 已提交
3311
		if (pte_file(entry))
N
Nick Piggin 已提交
3312
			return do_nonlinear_fault(mm, vma, address,
3313
					pte, pmd, flags, entry);
3314
		return do_swap_page(mm, vma, address,
3315
					pte, pmd, flags, entry);
L
Linus Torvalds 已提交
3316 3317
	}

H
Hugh Dickins 已提交
3318
	ptl = pte_lockptr(mm, pmd);
3319 3320 3321
	spin_lock(ptl);
	if (unlikely(!pte_same(*pte, entry)))
		goto unlock;
3322
	if (flags & FAULT_FLAG_WRITE) {
L
Linus Torvalds 已提交
3323
		if (!pte_write(entry))
3324 3325
			return do_wp_page(mm, vma, address,
					pte, pmd, ptl, entry);
L
Linus Torvalds 已提交
3326 3327 3328
		entry = pte_mkdirty(entry);
	}
	entry = pte_mkyoung(entry);
3329
	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3330
		update_mmu_cache(vma, address, pte);
3331 3332 3333 3334 3335 3336 3337
	} else {
		/*
		 * This is needed only for protection faults but the arch code
		 * is not yet telling us if this is a protection fault or not.
		 * This still avoids useless tlb flushes for .text page faults
		 * with threads.
		 */
3338
		if (flags & FAULT_FLAG_WRITE)
3339
			flush_tlb_fix_spurious_fault(vma, address);
3340
	}
3341 3342
unlock:
	pte_unmap_unlock(pte, ptl);
N
Nick Piggin 已提交
3343
	return 0;
L
Linus Torvalds 已提交
3344 3345 3346 3347 3348
}

/*
 * By the time we get here, we already hold the mm semaphore
 */
N
Nick Piggin 已提交
3349
int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3350
		unsigned long address, unsigned int flags)
L
Linus Torvalds 已提交
3351 3352 3353 3354 3355 3356 3357 3358
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *pte;

	__set_current_state(TASK_RUNNING);

3359
	count_vm_event(PGFAULT);
L
Linus Torvalds 已提交
3360

3361 3362 3363
	/* do counter updates before entering really critical section. */
	check_sync_rss_stat(current);

3364
	if (unlikely(is_vm_hugetlb_page(vma)))
3365
		return hugetlb_fault(mm, vma, address, flags);
L
Linus Torvalds 已提交
3366 3367 3368 3369

	pgd = pgd_offset(mm, address);
	pud = pud_alloc(mm, pgd, address);
	if (!pud)
H
Hugh Dickins 已提交
3370
		return VM_FAULT_OOM;
L
Linus Torvalds 已提交
3371 3372
	pmd = pmd_alloc(mm, pud, address);
	if (!pmd)
H
Hugh Dickins 已提交
3373
		return VM_FAULT_OOM;
3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 3393 3394 3395
	if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
		if (!vma->vm_ops)
			return do_huge_pmd_anonymous_page(mm, vma, address,
							  pmd, flags);
	} else {
		pmd_t orig_pmd = *pmd;
		barrier();
		if (pmd_trans_huge(orig_pmd)) {
			if (flags & FAULT_FLAG_WRITE &&
			    !pmd_write(orig_pmd) &&
			    !pmd_trans_splitting(orig_pmd))
				return do_huge_pmd_wp_page(mm, vma, address,
							   pmd, orig_pmd);
			return 0;
		}
	}

	/*
	 * Use __pte_alloc instead of pte_alloc_map, because we can't
	 * run pte_offset_map on the pmd, if an huge pmd could
	 * materialize from under us from a different thread.
	 */
3396
	if (unlikely(pmd_none(*pmd)) && __pte_alloc(mm, vma, pmd, address))
H
Hugh Dickins 已提交
3397
		return VM_FAULT_OOM;
3398 3399 3400 3401 3402 3403 3404 3405 3406 3407
	/* if an huge pmd materialized from under us just retry later */
	if (unlikely(pmd_trans_huge(*pmd)))
		return 0;
	/*
	 * A regular pmd is established and it can't morph into a huge pmd
	 * from under us anymore at this point because we hold the mmap_sem
	 * read mode and khugepaged takes it in write mode. So now it's
	 * safe to run pte_offset_map().
	 */
	pte = pte_offset_map(pmd, address);
L
Linus Torvalds 已提交
3408

3409
	return handle_pte_fault(mm, vma, address, pte, pmd, flags);
L
Linus Torvalds 已提交
3410 3411 3412 3413 3414
}

#ifndef __PAGETABLE_PUD_FOLDED
/*
 * Allocate page upper directory.
H
Hugh Dickins 已提交
3415
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3416
 */
3417
int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
L
Linus Torvalds 已提交
3418
{
H
Hugh Dickins 已提交
3419 3420
	pud_t *new = pud_alloc_one(mm, address);
	if (!new)
3421
		return -ENOMEM;
L
Linus Torvalds 已提交
3422

3423 3424
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3425
	spin_lock(&mm->page_table_lock);
3426
	if (pgd_present(*pgd))		/* Another has populated it */
3427
		pud_free(mm, new);
3428 3429
	else
		pgd_populate(mm, pgd, new);
H
Hugh Dickins 已提交
3430
	spin_unlock(&mm->page_table_lock);
3431
	return 0;
L
Linus Torvalds 已提交
3432 3433 3434 3435 3436 3437
}
#endif /* __PAGETABLE_PUD_FOLDED */

#ifndef __PAGETABLE_PMD_FOLDED
/*
 * Allocate page middle directory.
H
Hugh Dickins 已提交
3438
 * We've already handled the fast-path in-line.
L
Linus Torvalds 已提交
3439
 */
3440
int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
L
Linus Torvalds 已提交
3441
{
H
Hugh Dickins 已提交
3442 3443
	pmd_t *new = pmd_alloc_one(mm, address);
	if (!new)
3444
		return -ENOMEM;
L
Linus Torvalds 已提交
3445

3446 3447
	smp_wmb(); /* See comment in __pte_alloc */

H
Hugh Dickins 已提交
3448
	spin_lock(&mm->page_table_lock);
L
Linus Torvalds 已提交
3449
#ifndef __ARCH_HAS_4LEVEL_HACK
3450
	if (pud_present(*pud))		/* Another has populated it */
3451
		pmd_free(mm, new);
3452 3453
	else
		pud_populate(mm, pud, new);
L
Linus Torvalds 已提交
3454
#else
3455
	if (pgd_present(*pud))		/* Another has populated it */
3456
		pmd_free(mm, new);
3457 3458
	else
		pgd_populate(mm, pud, new);
L
Linus Torvalds 已提交
3459
#endif /* __ARCH_HAS_4LEVEL_HACK */
H
Hugh Dickins 已提交
3460
	spin_unlock(&mm->page_table_lock);
3461
	return 0;
3462
}
L
Linus Torvalds 已提交
3463 3464 3465 3466 3467 3468 3469 3470 3471
#endif /* __PAGETABLE_PMD_FOLDED */

int make_pages_present(unsigned long addr, unsigned long end)
{
	int ret, len, write;
	struct vm_area_struct * vma;

	vma = find_vma(current->mm, addr);
	if (!vma)
K
KOSAKI Motohiro 已提交
3472
		return -ENOMEM;
3473 3474 3475 3476 3477 3478
	/*
	 * We want to touch writable mappings with a write fault in order
	 * to break COW, except for shared mappings because these don't COW
	 * and we would not want to dirty them for nothing.
	 */
	write = (vma->vm_flags & (VM_WRITE | VM_SHARED)) == VM_WRITE;
3479 3480
	BUG_ON(addr >= end);
	BUG_ON(end > vma->vm_end);
3481
	len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
L
Linus Torvalds 已提交
3482 3483
	ret = get_user_pages(current, current->mm, addr,
			len, write, 0, NULL, NULL);
3484
	if (ret < 0)
L
Linus Torvalds 已提交
3485
		return ret;
3486
	return ret == len ? 0 : -EFAULT;
L
Linus Torvalds 已提交
3487 3488 3489 3490 3491
}

#if !defined(__HAVE_ARCH_GATE_AREA)

#if defined(AT_SYSINFO_EHDR)
3492
static struct vm_area_struct gate_vma;
L
Linus Torvalds 已提交
3493 3494 3495 3496 3497 3498

static int __init gate_vma_init(void)
{
	gate_vma.vm_mm = NULL;
	gate_vma.vm_start = FIXADDR_USER_START;
	gate_vma.vm_end = FIXADDR_USER_END;
R
Roland McGrath 已提交
3499 3500
	gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
	gate_vma.vm_page_prot = __P101;
3501 3502 3503 3504 3505 3506 3507
	/*
	 * Make sure the vDSO gets into every core dump.
	 * Dumping its contents makes post-mortem fully interpretable later
	 * without matching up the same kernel and hardware config to see
	 * what PC values meant.
	 */
	gate_vma.vm_flags |= VM_ALWAYSDUMP;
L
Linus Torvalds 已提交
3508 3509 3510 3511 3512
	return 0;
}
__initcall(gate_vma_init);
#endif

3513
struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
L
Linus Torvalds 已提交
3514 3515 3516 3517 3518 3519 3520 3521
{
#ifdef AT_SYSINFO_EHDR
	return &gate_vma;
#else
	return NULL;
#endif
}

3522
int in_gate_area_no_mm(unsigned long addr)
L
Linus Torvalds 已提交
3523 3524 3525 3526 3527 3528 3529 3530 3531
{
#ifdef AT_SYSINFO_EHDR
	if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
		return 1;
#endif
	return 0;
}

#endif	/* __HAVE_ARCH_GATE_AREA */
3532

3533
static int __follow_pte(struct mm_struct *mm, unsigned long address,
J
Johannes Weiner 已提交
3534 3535 3536 3537 3538 3539 3540 3541 3542 3543 3544 3545 3546 3547 3548 3549
		pte_t **ptepp, spinlock_t **ptlp)
{
	pgd_t *pgd;
	pud_t *pud;
	pmd_t *pmd;
	pte_t *ptep;

	pgd = pgd_offset(mm, address);
	if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
		goto out;

	pud = pud_offset(pgd, address);
	if (pud_none(*pud) || unlikely(pud_bad(*pud)))
		goto out;

	pmd = pmd_offset(pud, address);
3550
	VM_BUG_ON(pmd_trans_huge(*pmd));
J
Johannes Weiner 已提交
3551 3552 3553 3554 3555 3556 3557 3558 3559 3560 3561 3562 3563 3564 3565 3566 3567 3568 3569 3570
	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
		goto out;

	/* We cannot handle huge page PFN maps. Luckily they don't exist. */
	if (pmd_huge(*pmd))
		goto out;

	ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
	if (!ptep)
		goto out;
	if (!pte_present(*ptep))
		goto unlock;
	*ptepp = ptep;
	return 0;
unlock:
	pte_unmap_unlock(ptep, *ptlp);
out:
	return -EINVAL;
}

3571 3572 3573 3574 3575 3576 3577 3578 3579 3580 3581
static inline int follow_pte(struct mm_struct *mm, unsigned long address,
			     pte_t **ptepp, spinlock_t **ptlp)
{
	int res;

	/* (void) is needed to make gcc happy */
	(void) __cond_lock(*ptlp,
			   !(res = __follow_pte(mm, address, ptepp, ptlp)));
	return res;
}

J
Johannes Weiner 已提交
3582 3583 3584 3585 3586 3587 3588 3589 3590 3591 3592 3593 3594 3595 3596 3597 3598 3599 3600 3601 3602 3603 3604 3605 3606 3607 3608 3609 3610
/**
 * follow_pfn - look up PFN at a user virtual address
 * @vma: memory mapping
 * @address: user virtual address
 * @pfn: location to store found PFN
 *
 * Only IO mappings and raw PFN mappings are allowed.
 *
 * Returns zero and the pfn at @pfn on success, -ve otherwise.
 */
int follow_pfn(struct vm_area_struct *vma, unsigned long address,
	unsigned long *pfn)
{
	int ret = -EINVAL;
	spinlock_t *ptl;
	pte_t *ptep;

	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		return ret;

	ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
	if (ret)
		return ret;
	*pfn = pte_pfn(*ptep);
	pte_unmap_unlock(ptep, ptl);
	return 0;
}
EXPORT_SYMBOL(follow_pfn);

3611
#ifdef CONFIG_HAVE_IOREMAP_PROT
3612 3613 3614
int follow_phys(struct vm_area_struct *vma,
		unsigned long address, unsigned int flags,
		unsigned long *prot, resource_size_t *phys)
3615
{
3616
	int ret = -EINVAL;
3617 3618 3619
	pte_t *ptep, pte;
	spinlock_t *ptl;

3620 3621
	if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
		goto out;
3622

3623
	if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
3624
		goto out;
3625
	pte = *ptep;
3626

3627 3628 3629 3630
	if ((flags & FOLL_WRITE) && !pte_write(pte))
		goto unlock;

	*prot = pgprot_val(pte_pgprot(pte));
3631
	*phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
3632

3633
	ret = 0;
3634 3635 3636
unlock:
	pte_unmap_unlock(ptep, ptl);
out:
3637
	return ret;
3638 3639 3640 3641 3642 3643 3644
}

int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
			void *buf, int len, int write)
{
	resource_size_t phys_addr;
	unsigned long prot = 0;
K
KOSAKI Motohiro 已提交
3645
	void __iomem *maddr;
3646 3647
	int offset = addr & (PAGE_SIZE-1);

3648
	if (follow_phys(vma, addr, write, &prot, &phys_addr))
3649 3650 3651 3652 3653 3654 3655 3656 3657 3658 3659 3660 3661
		return -EINVAL;

	maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
	if (write)
		memcpy_toio(maddr + offset, buf, len);
	else
		memcpy_fromio(buf, maddr + offset, len);
	iounmap(maddr);

	return len;
}
#endif

3662
/*
3663 3664
 * Access another process' address space as given in mm.  If non-NULL, use the
 * given task for page fault accounting.
3665
 */
3666 3667
static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
		unsigned long addr, void *buf, int len, int write)
3668 3669 3670 3671 3672
{
	struct vm_area_struct *vma;
	void *old_buf = buf;

	down_read(&mm->mmap_sem);
S
Simon Arlott 已提交
3673
	/* ignore errors, just check how much was successfully transferred */
3674 3675 3676
	while (len) {
		int bytes, ret, offset;
		void *maddr;
3677
		struct page *page = NULL;
3678 3679 3680

		ret = get_user_pages(tsk, mm, addr, 1,
				write, 1, &page, &vma);
3681 3682 3683 3684 3685 3686 3687
		if (ret <= 0) {
			/*
			 * Check if this is a VM_IO | VM_PFNMAP VMA, which
			 * we can access using slightly different code.
			 */
#ifdef CONFIG_HAVE_IOREMAP_PROT
			vma = find_vma(mm, addr);
3688
			if (!vma || vma->vm_start > addr)
3689 3690 3691 3692 3693 3694 3695 3696
				break;
			if (vma->vm_ops && vma->vm_ops->access)
				ret = vma->vm_ops->access(vma, addr, buf,
							  len, write);
			if (ret <= 0)
#endif
				break;
			bytes = ret;
3697
		} else {
3698 3699 3700 3701 3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713
			bytes = len;
			offset = addr & (PAGE_SIZE-1);
			if (bytes > PAGE_SIZE-offset)
				bytes = PAGE_SIZE-offset;

			maddr = kmap(page);
			if (write) {
				copy_to_user_page(vma, page, addr,
						  maddr + offset, buf, bytes);
				set_page_dirty_lock(page);
			} else {
				copy_from_user_page(vma, page, addr,
						    buf, maddr + offset, bytes);
			}
			kunmap(page);
			page_cache_release(page);
3714 3715 3716 3717 3718 3719 3720 3721 3722
		}
		len -= bytes;
		buf += bytes;
		addr += bytes;
	}
	up_read(&mm->mmap_sem);

	return buf - old_buf;
}
3723

S
Stephen Wilson 已提交
3724
/**
3725
 * access_remote_vm - access another process' address space
S
Stephen Wilson 已提交
3726 3727 3728 3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739
 * @mm:		the mm_struct of the target address space
 * @addr:	start address to access
 * @buf:	source or destination buffer
 * @len:	number of bytes to transfer
 * @write:	whether the access is a write
 *
 * The caller must hold a reference on @mm.
 */
int access_remote_vm(struct mm_struct *mm, unsigned long addr,
		void *buf, int len, int write)
{
	return __access_remote_vm(NULL, mm, addr, buf, len, write);
}

3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 3751 3752 3753 3754 3755 3756 3757 3758 3759 3760
/*
 * Access another process' address space.
 * Source/target buffer must be kernel space,
 * Do not walk the page table directly, use get_user_pages
 */
int access_process_vm(struct task_struct *tsk, unsigned long addr,
		void *buf, int len, int write)
{
	struct mm_struct *mm;
	int ret;

	mm = get_task_mm(tsk);
	if (!mm)
		return 0;

	ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
	mmput(mm);

	return ret;
}

3761 3762 3763 3764 3765 3766 3767 3768
/*
 * Print the name of a VMA.
 */
void print_vma_addr(char *prefix, unsigned long ip)
{
	struct mm_struct *mm = current->mm;
	struct vm_area_struct *vma;

3769 3770 3771 3772 3773 3774 3775
	/*
	 * Do not print if we are in atomic
	 * contexts (in exception stacks, etc.):
	 */
	if (preempt_count())
		return;

3776 3777 3778 3779 3780 3781 3782 3783
	down_read(&mm->mmap_sem);
	vma = find_vma(mm, ip);
	if (vma && vma->vm_file) {
		struct file *f = vma->vm_file;
		char *buf = (char *)__get_free_page(GFP_KERNEL);
		if (buf) {
			char *p, *s;

3784
			p = d_path(&f->f_path, buf, PAGE_SIZE);
3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797
			if (IS_ERR(p))
				p = "?";
			s = strrchr(p, '/');
			if (s)
				p = s+1;
			printk("%s%s[%lx+%lx]", prefix, p,
					vma->vm_start,
					vma->vm_end - vma->vm_start);
			free_page((unsigned long)buf);
		}
	}
	up_read(&current->mm->mmap_sem);
}
3798 3799 3800 3801

#ifdef CONFIG_PROVE_LOCKING
void might_fault(void)
{
3802 3803 3804 3805 3806 3807 3808 3809 3810
	/*
	 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
	 * holding the mmap_sem, this is safe because kernel memory doesn't
	 * get paged out, therefore we'll never actually fault, and the
	 * below annotations will generate false positives.
	 */
	if (segment_eq(get_fs(), KERNEL_DS))
		return;

3811 3812 3813 3814 3815 3816 3817 3818 3819 3820 3821
	might_sleep();
	/*
	 * it would be nicer only to annotate paths which are not under
	 * pagefault_disable, however that requires a larger audit and
	 * providing helpers like get_user_atomic.
	 */
	if (!in_atomic() && current->mm)
		might_lock_read(&current->mm->mmap_sem);
}
EXPORT_SYMBOL(might_fault);
#endif
A
Andrea Arcangeli 已提交
3822 3823 3824 3825 3826 3827 3828 3829 3830 3831 3832 3833 3834 3835 3836 3837 3838 3839 3840 3841 3842 3843 3844 3845 3846 3847 3848 3849 3850 3851 3852 3853 3854 3855 3856 3857 3858 3859 3860 3861 3862 3863 3864 3865 3866 3867 3868 3869 3870 3871 3872 3873 3874 3875 3876 3877 3878 3879 3880 3881 3882 3883 3884 3885 3886 3887 3888 3889 3890 3891 3892

#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
static void clear_gigantic_page(struct page *page,
				unsigned long addr,
				unsigned int pages_per_huge_page)
{
	int i;
	struct page *p = page;

	might_sleep();
	for (i = 0; i < pages_per_huge_page;
	     i++, p = mem_map_next(p, page, i)) {
		cond_resched();
		clear_user_highpage(p, addr + i * PAGE_SIZE);
	}
}
void clear_huge_page(struct page *page,
		     unsigned long addr, unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		clear_gigantic_page(page, addr, pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		clear_user_highpage(page + i, addr + i * PAGE_SIZE);
	}
}

static void copy_user_gigantic_page(struct page *dst, struct page *src,
				    unsigned long addr,
				    struct vm_area_struct *vma,
				    unsigned int pages_per_huge_page)
{
	int i;
	struct page *dst_base = dst;
	struct page *src_base = src;

	for (i = 0; i < pages_per_huge_page; ) {
		cond_resched();
		copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);

		i++;
		dst = mem_map_next(dst, dst_base, i);
		src = mem_map_next(src, src_base, i);
	}
}

void copy_user_huge_page(struct page *dst, struct page *src,
			 unsigned long addr, struct vm_area_struct *vma,
			 unsigned int pages_per_huge_page)
{
	int i;

	if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
		copy_user_gigantic_page(dst, src, addr, vma,
					pages_per_huge_page);
		return;
	}

	might_sleep();
	for (i = 0; i < pages_per_huge_page; i++) {
		cond_resched();
		copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
	}
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */